Which forums do you speak of?
I know new 12/13 inch pro units are coming out but my budget is 700-750.
There's a marketplace here -- you can typically use Paypal to make payments, and people can provide you with their eBay IDs or their IDs on another feedback system (like Heatware) so that you know they're safe. I've bought and sold here a number of times, including an iMac, and I've been very happy. We don't let anyone totally new post for sale threads, also for your safety.
https://forums.macrumors.com/forums/14/
If you are really willing to spend $700-750, I almost certainly think that what you want is a MacBook (not pro). A used one should be available for that price, probably from the first (Core Duo, not C2D) generation. Unless you specifically need the lighter / smaller PB (it's about 2/3 lb lighter), the longer battery life (if the battery is in good condition), or the PPC processor, the MB is the way to go.
The model I'm recommending is this one:
http://apple-history.com/?page=gallery&model=mb&performa=off&sort=date&order=ASC
If you really don't want to spend that much money, and you're after something more like that $450-475 or so, I would recommend a 12" iBook with a 1.0-1.2 GHz processor, which you should be able to find if you're patient, at that price.
In fact,
Haoshiro, who's a good guy, just posted that he's selling one.

(EDIT: although his is somewhat nicer spec-wise than that and probably would command slightly more money)
https://forums.macrumors.com/threads/330924/