Two.
I guess they didnt because it clearly said it has 328P chip inside...
And what would be the right thing to do ?
They were quite clear that it is a 328p compatible in the title, and from the eBay page:
"Package Content:
1 x ATmega328P Version Board
1 x USB Cable"
They
didn't say "1x Compatible board with ATMega328P installed" But they were not clear that it is NOT installed with the ATMega32P - except in the picture.
Frankly, if I am eBay adjuster and I got the complain, I probably rule with the seller.
What remains an open issue is, how compatible is it and when you do get your bootloader-loaded MCU, will it work and how well.
Perhaps once you get it working, subtracting the cost of the new pre-loaded MCU, contact the seller and pay him back the difference, so you got a couple of extra chips you can learn to burn boot-loaders with, and the seller get a hell of a good day knowing there are good people out there - he probably doesn't understand what you are trying to do anyway because many of the sellers are awful with their English.
An alternative is merely donate a portion of the difference to your favorite charity...
Next time when you walk by those donation box/jar, just be a little more generous.