I run a single Sundown SA-10 on 1200w. You could easily get a pair of SKARs or Sundowns for under 200 a piece, and both would easily take 1000w each. For a cheap amp that does rated, I'd recommend an Audiopipe 1800. And then prepare to spend the money that you saved buying better subs for less, on a proper box, designed and built by a professional, for your specific subwoofers. In fact, you could buy a pair of SKAR 12's with a D4 voice coil right here:
*B-Stock* SKAR Inventory For Sale - Car Audio Classifieds
for $260 shipped to your front door. That's for the pair.
For the amp
1500d:
Audiopipe AP15001D | 1500W Audiopipe Mono D Amplifier : $147.95 : VMInnovations.com
1800d:
Audiopipe AP1800D 1800W Mono Power Amplifier : AP18001D : $191.95 : VMInnovations.com
I think the 1500d would be better for you, so you don't risk ruining the subs as easily. And you won't be able to hear the difference in power, so no worries about that.
So then you're out $410 for subs and amp. And you have plenty of money left for the proper electrical upgrades, and subwoofer enclosure to be built.
Oh, and I've heard a pair of the SKARs on an Auidopipe, and it will blow your mind away. More literally, it'll blow your hair away.