If you go with Avid specs you’re going to have to spend some money, but your system will be stable and it’s the smartest thing to do.
For the best bang for your buck I’d suggest checking out HP’s refurbished site. I know a guy that got an xw8200 that met every Avid spec, and he paid about $1,700–about half the price of what it used to cost new (and still does, I think). Buying refurb will get you a great system, warranty, and will run your Avid happily. Otherwise, if you’re computer savvy, build your own system EXACTLY to Avid spec and hope for the best.
Unfortunately, there’s really no cheap way to run Avid. If you go outside of spec you’ll have a system that won’t run at all, won’t run well, or will run great–there’s no way to tell, so it’ s gamble.
Hope this helps.
Mike.