you need to measure the space you have available. Having someone build a box is going to cost around a 1/4 of your budget. A ported box is going to be larger then your sealed boxes. If I were you id use the pioneer it'll do 450 rms bridged. Get one sub, size of sub based on the room you have so you can add another latter when you can afford it.
so if you go out and buy a two hundred dollar sub 200 $ amp 200$ box you still only have one sub and u still need to buy everything to hook it up.
you'll need a 4 ohm sub or a 2 ohm dual voice coil sub wired to 4 ohm to run off the pioneer bridged. One good sub in a good ported box is going to sound way better then your two different sized sealed kickers. That's what id do anyway.