Well I'm not sure about the answer to your question, but you might be able to find JL Audio's 5 channel used or on
ebay or used for about that price, and that seems like that might be a really nice amp. I'm not sure what other decent 5 channels are out there, but there's not a whole lot of them either.
I ran a 5 channel for a long time, a PPI 5440. Two of the channels blew, and so I used it as a 3 channel amp, with great results.
My point is, depending on your speaker configuration, you might be able to buy a 4 channel amp and get WAY more bang for you buck. I have spent the last week shopping around for a replacement for my amp, was originally trying to find a 5 channel, but decided against it when I found way better deals on more powerful 4 channel amps. I just paid $260 (incl shipping) for an Alpine MRP-F600. Yes, you lose a tad bit of flexibility when losing that 5th channel, but to me it wasn't a big deal. Think about it...JL's 500 watt 5 channel for $500, or Alpine's 600 watt 4 channel for $260? And to me, the most important spec was the power on the sub channel. The JL was 250 watts, while the Alpine is bridgeable to 300 watts.
What are you trying to run off of your amp?