audiopipe 1500d is a nice amp it will give you some head room if u want to upgrade your speakers. i have 4 12inch tidal audio subs there 80.00 and for the most part i like them. the fs is 20 and the xmax on these are 17mm not bad for 300rms subs.
im thinking of goim that route also , 4 comp 12s, I only have 600 at 1 ohm though. Which is their rated power. as stated earlier, the audiopipes on ebay for 150 ish is you most power for the money.
just build it already, go to walmart and get a 4 ga amp kit and a roll of 14ga speaker wire and youll be fine. Dont need to overspend on a budget build. should get plent loud.