Either company's amps represent a significant "bang for your buck," I would say. Emotiva is a newer internet-direct brand than Outlaw, and the amps you mention (certainly the XPA-5) are new enough that I would not expect them to appear yet in the used market. My dealings with Emotiva have mainly been related to discussions regarding an older surround processor (the LMC-1, now discontinued) and while those dealings were not necessarily positive, they also don't relate to the actual hardware of those amplifiers. Their amps are built overseas (China, specifically), unlike Outlaw's US-built multichannel amps, and that is going to be responsible for some of the price differential. It's not the only reason for the price difference though, as there's too much disparity for that to be the only factor involved. I was actually looking at some of the pictures of and specs on their newer amps earlier this week, and noticed one or two things. First, the XPA-5 (their 5x200W amp) appears to have smaller heat sinks than the 7500 (the transformer takes up more of the depth than the 7500's pair of transformers). Heat rejection is certainly important, and I'd suspect that the 7500 would have an advantage here. Second, the 7500's signal-to-noise ratio is about 20dB better (120dB vs. 100dB). This, moreso than the extra heat rejection, is likely to yield benefits sonically. I don't know what differences might exist for factors such as crosstalk, which aren't represented in either amp's specs.

Are the Emotivas good amps? I'd expect them to be a step or two up from the typical receiver's internal amps, without a doubt. Are they as good as the Outlaw amps? The SN ratio numbers suggest that they might not be, but I haven't heard an XPA-5 to know just how it might compare to my 7500.