I've bought things a few times in my life (mainly from Woot when they actually had good prices) with the hopes of selling on eBay. It's really not so easy IME especially nowadays when people can normally find things priced just as low (or cheaper) on other sites than on eBay. But, if you can do it, I don't see why it wouldn't work.
+1, has to be a great deal. I bought a bunch of the nuud cases from groupon a couple months ago. I was making from $5 to losing $5 on each one. The last couple weeks I was losing closer to $10 on the last 3 I sold, but then my last one sold for close to $90 when all others were going for like $38 with shipping, so I broke even, but it's a risk.
As Yehuda said, before amazon bought woot, they had amazing deals - I'm looking at you sansa clips for $10 that sold on ebay for $25 - but now it's pretty crappy. I don't even bother going when there's a woot off anymore.