Having owned an A500, 600, 1000, 1200, 3000, 3000T, 4000D, 4000T...cdtv and CD32
An A4000D or 4000T is the best bet (aga and maximum comapatiblity with modern upgrades) My A4000T had the CSPPC/060, 128 megs, Cybervision PPC, video toaster flyer, DCTV, TBCIV, Peggy plus, Scala (with a scala badge over the amiga badge) It was a great machine with BOTH scsi and IDE.
The A3000 for $3 is great. A graphics card is of use only if you want to play games that support the graphics card.
The picasso IV is good, even the EGS Spectrum is nice, Stay away from the Z2 Retina. A card that can pass through the signal and switch between the A3000 video and the graphics card is ideal.
The BIG plus is the A3000 is VGA out of the box, scsi drives are a dime a dozen on ebay or
www.justdeals.com, people give away old scsi cd-roms.
You're lucky, aside from a $35 A1200 I recently scored I've paid with sweat, blood and hard earned duckets for all my amigas.
Oh and for the living room? An xbox running UAE on a lcdtv.
AGA, ECS and hardfile support plus every other emulator you can think of.