Not sure if I have Mealy Bugs or not

[NYCorchidman]

How big are the white stuffs??
It could be scales. They are very small, like 1mm.
Mealy bugs are quite small when young, but all of them would move when poked with something like, say, toothpick. So give it a try.

Scales are quite common on cattleyas.

By the way, nothing wrong with buying orchids on eBay. It is just the same as ordering orchids from a vendor, except many times, with eBay, you get to see exactly what you are getting.