If you buy RAM from OWC, you don't need to concern yourself with who made it. OWC will stand behind it regardless.
I should be able to get around that expandability somewhat by using a external esata drive dock.
Be careful what eSATA adapter you buy. Some haven't been very successful at all with early unibody MBPs. If I were you, I'd just stick with FireWire 800 for external drives.
It appears that one of the few places that still has this model is Amazon, and at $2800 that is a lot more than I paid for it (even if you do not include the Apple rebates and high end Cannon printer I got free with it and later sold).
It's also way, way more than anyone anywhere is going to pay for an outdated machine now. I can't imagine what Amazon is thinking about, putting that price on it. Is that in US dollars?
You will have to undercut Amazon's outlandish price by at least $1400 to sell your machine. To see what that model is really selling for, check completed sales of it on Ebay. That's where the market value of everything movable is determined nowadays. New-in-the-box condition won't add much to the machine's value, because its warranty has expired.