Q: How do get data from '87 Apple 40 meg SCSI to new iMac?

That's a rather tricky question, especially given the  nature of your finances.     You might want to call around http://www.apple.com/usergroups/ and find out if anyone has a PowerMac G3 beige.   Those are excellent bridge machines that offer SCSI connectivity and access to newer Mac operating systems.

Data recovery can be very expensive (i.e. thousands of dollars) for someone who can do it right.     But sometimes all that is needed is Prosoft Data Rescue, and it can extract information from nearly dead hard drives.

If someone were to give you that computer (one of the short-lived Mac "clones"), it would enable you to retrieve the data from the old SCSI hard drive, but then you'd have to decide how to transfer the files beyond that computer - perhaps by networking it with another computer.  This can present compatibility issues, depending on how many years separate the OS versions in the two computers to be networked.  Personally, I'd prefer one of Apple's Power Macs — Desktop: 7300, 7500, or 7600, a mini-tower 8600 or 9600, or a beige G3 desktop or mini-tower model.  If any of these models were running OS version 8.6, 9.0, 9.0.4, or 9.1, you could install a USB PCI card and transfer the files directly from the SCSI hard drive to a USB flash drive.  Be advised that the OS build on that 40 GB drive won't boot any of these models, so it would need to be connected as a second drive internally.  You'll need to change its SCSI ID address from the default "0" by moving the plastic jumper.  Since neither SCSI address "1" nor "2" is typically used by factory-default, I often set the second internal SCSI hard drive's address to "1."  You'll likely find that its "TE" (Termination Enable) jumper is installed, and that will need to be removed, because only the last device connected to the ribbon cable should have termination enabled.  The beige G3 series has a shared internal/external SCSI bus, but unless it's a first revision G3 with a SCSI Zip drive, you'll need a 50-conductor SCSI ribbon cable to connect to the 40 MB drive.  If it has a SCSI Zip drive, you could remove it and connect your 40 MB drive in its place, leaving the SCSI address and termination jumpers set the way they are.  A beige G3 has an IDE/E-IDE (not SCSI) hard drive and an ATAPI optical drive.

If it's the one I saw listed that's sitting at ~$12, the added shipping weight/cost would be my greater concern.  I don't know if you're aware of it, but that Starmax motherboard doesn't have an internal SCSI bus for connection of a ribbon cable and your hard drive.  The SCSI bus is only usable via an external DB-25 port.  This means that you'll have to find an external SCSI enclosure for the hard drive (they usually had a pair of Centronics-50 ports on the back of them) and the heavy 50-conductor SCSI cable with a DB-25 connector on one end and a Centronics-50 at the other end.  The unused Centronics-50 port on the enclosure needs to be terminated with (preferably) an active SCSI terminator, although a passive one might suffice.  About 10-15 years ago, I paid $14 each for the active terminators used with my SCSI external peripherals.  The active terminators provided a more stable operation of the peripheral, than the passive type.

The main idea behind the Apple clones was to design/build a Mac computer that incorporated less expensive "PC" components, which is why the Starmax had an IDE hard drive, ATAPI CD-ROM drive, and no internal SCSI bus.  Apple made the transition to IDE and ATAPI devices beginning with the beige G3s, but still included a shared SCSI-1 internal/external bus.  Onboard SCSI was abandoned with the next generation of G3s - the Blue & White models.  In models having a SCSI bus, it was provided by a PCI card.  In terms of processor speed, the Power Mac 7300 desktop computer had the same 604e/200 MHz processor as the Starmax 4000, although the 7300 had a processor card slot.  This made it much easier (for those of us who owned them) to substitute faster processors - like a G3.

If that's the case, it should be straightforward enough.  I had reservations about the need to find/purchase the necessary external paraphernalia for an internal hard drive.  If the shipping expense isn't too much, then it would be a good choice.  I don't know if there are any thrift stores in your area, but donated older computers do show up at stores like that.  If you could find a suitable older mac, it would eliminate the ebay route and shipping expense.  The last beige G3 desktop that I saw in a thrift store (about 5 years ago) was only $20 and was in mint condition.  I passed on it because I just didn't need another beige G3.

I kept (in basement storage) my upgraded G3 beige precisely because it has everything from SCSI, IDE, USB, Firewire, Zip, 3.5" floppy, CD&DVD.

Of course if you get a computer you will also have to have a monitor which will plug into it.  All my stuff is old technology so I don't know if a newer monitor can still work with older computers, even if you have an adapter.

One issue with getting a used computer may be the PRAM battery. Be prepared for possibly having to get a new one (not sure how easy that may be since they are an odd size).

Roughly where in the world are you located?

If you're located near the seller of that Starmax, there is an active Apple User group not far (less than 10 miles) from there.  If you were to contact them, perhaps you could take your peripherals to their location and they'd help you transfer your files without you having to buy any hardware?

Goodwill stores in my area haven't accepted computers in years.  I think they were being saddled with recycling costs from too much old stuff with very limited return vs. time investment to see if it even still worked.  You can still find old peripherals. For Apple an old computer is anything 4+ years. For most people that stretches to 6 years.  Anything G3 vintage is now considered by most to be completely useless and may be hard to find because everybody got rid of them 10 years ago.

You might be better off looking at Craigslist. I know that's how I gave away of some extra G3s (not the one still in my basement) about 4 years ago.

Out of curiosity, I just checked ebay for a Power Mac 7300, 7500, 7600, 8600, and beige G3.  There were some parts, but not an entire computer.  It seems like not so many years ago when one would get a reasonable number of listings for any of them.  There are some listings for Blue & White G3s.  Unfortunately, technology and obsolescence eventually cross paths, providing some of us with expensive doorstops that are still in mint condition.