Yeah, basically two great pieces of advice already. Second hand kit is almost definately the best thing for you to buy if you're starting out. If you bought a mechanical marker and got into paintball properly like said above you'd be looking to sell it as fast as you can hehe. Im not sure how much the Trilogy cockers are selling for these days. But im sure for a tiny bit more you could get a second hand Eblade cocker which would be far greater value for your money.
You should be careful with cockers, dont listen to everything people say about them, generally speaking they are very reliable guns and if taken care of thoroughly should serve you very well indeed. There are some aspects of them which can go wrong, particularly the timing of the cycle etc, but thats something which with a little bit of know-how can easily be resolved.
I would say that if you are looking for a gun, a second hand E1 Cocker or an Ion or something like that would serve you perfectly. Like said above, I think you will really feel the need to upgrade if you start with a mech cocker, and also the resale value on them is terrible at the moment.