I actually just picked up a 2007 bowtech off of craigslist for $300. I was using my dad's old bow and had no idea about draw lenght or weight. I still killed deer with the bow but I am blown away with how much better the new bow is. Plus your arms and shoulders will thank you for the 70-85% let off of the new bows compaired to the (what felt like 0%) let off of the old ones.
Just be warned that, even if you don't have an adictive personality, the first time you shoot a deer with a bow you will be hooked for life.