Do yourself a favor, get a good 10" sub, Fosgate,JBL,Orion, Infinity, JL, Kicker or Cerwin Vega. Then a HIGH QUALITY 100 Watt amp, like a Orion,Fosgate,or Soundstream.
Put in a sealed box that is the manufacturer's recomended size, this is important because unlike popular opninon, just because the hole is cut the right size, doesnt mean the box is the correct on for the sub.
The Amp is very critical to good sound as well, If you see a 400 Watt Profile amp with shiny chrome finish and tons of flashy lights for $200, then come across a plain blue, Soundstream 100 watt for $400, there IS A BIG REASON for that. The soundstream will always sound better, provide cleaner, more acurate power, and most likely last a lot longer as well...