Don't lock yourself into the box sets. Sometimes the individuals are cheaper especially if the box set is new. Unless of course the person ONLY wants the box set, though that seems odd since the show is still going.
Walmart.com and gohastings.com also have pretty good new retail prices.
Right now the cheapest is $41, but that will probably go up to $61 by the time the auction ends (8 hours). The sellers are all legit, all have 100% positive reviews and have sold thousands of things to customers so you dont need to worry. Ebay is very good and gets a bad rap on here for some reason.