well the good thing to come out of this amp. You can always use it for your front stage, and get a real class D and run the CVX at 1ohm as opposed to 4ohms.
On the cheaper side, this is what I would suggest. You could move down to a 800w amp, but atleast you have head room with the extra 200w.
http://www.woofersetc.com/index.cfm?fuseaction=product.display&Product_ID=6640
This should meet your budget.
2 of these..
http://www.woofersetc.com/index.cfm?fuseaction=product.display&Product_ID=6565
with this..
http://www.woofersetc.com/index.cfm?fuseaction=product.display&Product_ID=6640
Well, what is your budget, and which model of ID subs are you looking into?
Best bet is show us your entire budget with a breakdown on how you would like to spend it. Also, will your budget need to include wires, box, etc.