I would get rear leafs and front coils and a front sway bar to start, that's you're biggest bang for the buck, I also would get them all from the same company, I started my own build the same way, you will be happy with that start, and a good set of shocks for 2500 you can do well



Leafs about 400 bucks
coils about 200 bucks
sway bar 250 bucks
shocks.......500 bucks

that's a good start