Two problems with those cards:
1. The Professors are very limited in how many they can get. I can't remember, maybe 3 packs of each? That's a playset with two spares.
2. They're kind of a badge of pride, so most who get those will want to keep at least a playset of them.
As far as price goes, there haven't been any on eBay. XD So it's pretty much whatever they want to ask. I'd put them somewhere between $2 and $10.