Getting a bike

Hey gang.

I had hoped to be trying a few races this year, but it just didn't happen because of all this weight I've gained (P90x, here I come). I currently ride a Trek Antelope 800 series mountain. It's been a loyal bike that I found in a garbage heap. I was going to modify it for cross, but it's so darn heavy. (I had tried Iron Cross here in PA with it, and carrying it up the one part practically killed me). So I started looking around for tossed bikes that I could build a frankenbike from. I've found some nice components I can strip off, but it's been discouraging finding a frame that fits me and that can be modified for cross. 

I've cruised Craig's list, to no avail. Everything is so far out of my price range. Yes, I want a nice bike, but the reality is I'm going to enter, at best, a handful of races just to have a good time. I can't break the bank (nor have said bank to break). 

So I guess I have two questions: Any tips or advice on how I can put together something I can race, but also adapt for some road/trail riding around here, as inexpensively as possible? And 2, I was checking around the Web last night and found this bike: http://www.bikesdirect.com/products/gravity/liberty_cx.htm. It's rather cheap, but I also have read both very positive and very negative reviews about the quality of bikes from this vendor. Any one have any constructive advice on this particular bike, knowing what I'm looking to do? 

Much thanks.