You can have my XL for $1,000

Yeah, there are tons of great older bikes around. My first, a 1980 CB650 custom was a great bike and I didn't do anything to it... except beat on it. Probably the best $800 I ever spent!
To be honest, if I were in the market for another bike, I'd probably get an nice old big bore Suzuki GS and "tune" it a bit. Superbike bend bars, piggy back shocks, filters, pipes, braced swing arm etc.
With a nicely done old bike you've got 90% of the street performance of a new bike but never the buyers remorse that comes when the next "bigger, better, faster" model comes out

Anyway, back to the original posters question, pretty well any reasonable condition older 650 or smaller will be a fine bike... the ones suggested are just what we consider the "best" or easiest to own for a first bike.
As far as value is concerned... I find eBay a good source. As long as there are a bunch of "said bike" listed you can generally get a reasonable idea of the value. Adjust for ease/hardship of getting a bike to where you are and there's a reasonable price.
Chris... conasure of grungy old bikes