Well, you're not exactly right sytrax. All paints are not created equal. You need a good barrel that matches the paint you shoot, and you need your marker to be as consistant as possible. Nitro will help alot to this end, but you have to remember, you have an entry level marker, and it can only be made so much better before you hit a wall. A stock cocker on co2 will shoot a helluvalot better than a spyder on n2. both of which cost about the same.
for a little bit more, you could buy an impulse, then when you have the money, buy n2 for it.
As for top paint brands, RPS/PMI Advantage shell stuff works great, as well as diablo inferno, and the ZAP stuff. I usually say go buy what's most expensive. But, if you go out and try and shoot imperial hellfire through a spyder, you'll make some soup ...
-Micah