what mods you have now?
You are going to need some gaskets, perhaps a new top end(since you already have it down) if you have low psi, oils, supporting mods like pipes, air filters etc. Heck, a tors removal kit if your bike doesnt have one already. All of that will make you go well over your expected price. You are also going to want to pick up a Clymer manual so you know what to do.
I think you need to sit down and research A LOT more. If you bike is stock, simple bolt ons will do fine. Maybe just throw on a pipe, air filter and some decent shocks/a-arms and call it quits for a while. Then worry about more power. I really dont see the need for all kinds of power if you do trails a lot. Id go for some decent suspesnion and be done with it.