Depends on the size. For a 270a amp, ive sse nit range from $400 to $600 for my car.
PM them. I didnt see my car on DC, Mechman, or Iraggis old site, but i PMed them and they could make it.
I would replace the starter battery and add one in the back. Also, I'd put in some aftermarket mids and highs if you didn't do that already..you'll need the tweets
Id never put the lvl2 on 1krwms. An amp for those level 4s is the AQ2200D. Its $389 new last time I checked.
Here are some used amps:
http://www.caraudioclassifieds.org/forum/showthread.php?t=53569
http://www.caraudioclassifieds.org/forum/showthread.php?t=53598
http://www.caraudioclassifieds.org/forum/showthread.php?t=53480
http://www.caraudioclassifieds.org/forum/showthread.php?t=53603
I just thought of something. The Crescendo 3kwp has apparently the same board as the SAZ-3000D. The specs on Crescendo's site say the 3kwp puts out 4030 watts at .5 ohm at 13.8 volts. Wouldnt that blow the Level 4? Do you guys think the XLs would like that power more?