US AMPS has a good one that is comparable to the JL 500/1 and for alot cheaper price. Look at the XT-1000D. This is also the sister site to RE AUDIO which is a really high end brand. This is also a mono block amp. JL can be tricky though as they can handle far more than there RMS states. 500RMS is what they claim, Im sure they can do 1000 easy but it will void the warranty and might blow not saying they will but it would be a chance. Ebay has them for 181.98 with free shipping. Guy is a power seller with more than 10 available and 99.4% positive feedback.
http://cgi.ebay.com/US-AMPS-XT-1000...MPLIFIER-_W0QQitemZ360125921683QQcmdZViewItem
* Brand New US Amps Xterminator XT-1000D 500W RMS 1 CH Mono Class D Mono Amp
* 75W RMS x 1 @ 4 Ohms
* 150W RMS x 1 @ 2 Ohms
* 500W RMS x 1 @ 1 Ohms
* Variable Crossover Control : Low-Pass 40Hz-250Hz, 24dB/Octave, Butterworth
* Variable Bass EQ : 30dB Boost @ 45Hz
* Subsonic Filter: 15Hz - 40Hz, 24dB/Octave
* Low Level RCA Input
* Low Level RCA Pass-Though
* 8 Gauge Power Inputs
* 8 to 18 Gauge Speaker Terminals
* Power and Protection Indicators
* Class D Amplifier
* Dimensions: 2-1/2"H x 8-3/4"W x 9-3/4"L
http://usamps.com/xt_amps.html