What do you mean? Mwave gets what I paid - fees. The seller isn't taking a hit on these deals. They simply reap the benefits of the huge rebates....in my case, it was 30% from MS, 10% from Ebay and $40.00 from Evga.
I mean the Ebay fees for buy it now are about 12% (or maybe 10%), plus 3% for Paypal. So MWave loses $40 to Ebay on a $260 sale. Ebay and MS probably both pay for the deal, and I'd guess Ebay pays most of it, since they are the only ones with such high % off.