To get Lion you first need to buy Snow Leopard here: http://store.apple.com/us/product/MC573Z/A
The reason you need Snow Leopard first is that it includes the App Store, which is the only way to buy Lion:
OS X Lion system requirements
To use Lion, make sure your computer has the following:
- An Intel Core 2 Duo, Core i3, Core i5, Core i7, or Xeon processor
- Mac OS X v10.6.6 or later to install via the Mac App Store (v10.6.8 recommended); you can install without Mac OS X v10.6 by using an OS X Lion USB Thumb Drive, available on the Apple Online Store
- 7 GB of available disk space
- 2 GB of RAM
If your Mac does not meet these requirements, you will need to upgrade your Mac before installing Lion. For more information, see OS X Lion - Technical Specifications.
The 2 GB memory requirement is very marginal. Most people recommend a minimum of 4 GB. I can't find an iMac2,1 anywhere but if it's a Core 2 Duo I'm estimating it is a late 2006 model?
Models introduced in 2007 were available with 4 GB and those are the earliest ones I would recommend for Lion. It's a memory-hungry beast.
Hopefully this was more useful than having Apple hang up on you. That's intolerable.