Used/refurb ---> ebay.
Personally I would avoid any of the lower end pioneers (i.e. all non-elite models other than vsx-101x) if I could help it - if any of the channel(s) fail it's automatically $30-$65 in parts alone, depending on the model. I have no idea of the possibility/prevalence of this happening, all I know is that it does happen and is often not worth repairing (based on the unit's value); possibly this is due to using a woefully undersized heatsink and fan cooling that is controlled only by signal levels and not temperature (they run a bit hot to begin with at idle).
Onkyo & Denon units have a good reputation for meeting their advertised wpc rating, not so much in the case of Sony & Yamaha. Onkyo's are always a good option although I find them to be ugly & would prefer Denon given the choice. H/K's ratings are pretty accurate, although only because they are rated somewhat low to begin with - this may be a problem if you have inefficient speakers. Onkyo's tend to run quite warm/hot at idle, this could be a factor depending on your placement.
You could
possibly pick up something like a VSX-1014TX-K (for example) for under $200 - I looked on ebay and 3 working units in good condition sold for $82, $162, $285 (last one may be a fluke). The VSX-101x units inherit the pioneer elite platform with less features/inputs (VSX-1019 exempted) which is why they are a good option. H/K (
Harman Audio) sells refurbs directly on ebay with a factory warranty, possibly something to consider.
If you're set on the 816 for whatever reason, I have one right here if you have any questions.