If you wanted to send each sub 500 watts rms you are going to have to look for an amp that can do 1000 watts rms X 1 @ either 1 ohm or 4 ohm.
However I doubt that those subs can actually handle that much power, so I'd recomend to find an amp that will do around 700-800 watts rms x 1 @ 1 or 4 ohms.
You can look for a 2 channel amp that will bridge to send that much power, most will bridge and be 4 ohm stable.
You can look for a mono channel amp that will do 700-1000 watts rms @ 1 ohm.
Or you can get a 4 channel amp that willl bridge to a 2 channel to send each channel 300-500 watts rms @ 4 ohm.
You're going to be hard pressed to find anything decent for 150 bucks, that will send enough power to them, although they probably can't handle that much power.
What I would do is get a Zed Minilith, they cost 200 bucks plus shipping, and is a very good amp. It will do 650 watts rms X 1 A 1 ohm, then in the future if you ever plan to upgrade subs, you will have a good amp.
www.zedaudio.com