I have been using a Paradigm DSP3400 with my Axioms for the last 2 yrs to good effect. Price at the time was $700 CAD with some minor haggling but I think they'd likely go for $800ish + these days. To be fair, I've not heard an Axiom sub as of yet, so I'll reserve any comparison to the EP350 or EP500, but so far, I'm very pleased with the Paradigm.

Half of communication is listening. You can't listen with your mouth.