I was looking on ebay because I was thinking about selling my criterion killer DVD and I noticed that were lots of auctions for 20-30 but 3-4 for over 200.00. Is there a lot of bootlegs running around of the criterion edition?

Ebay is overrun with bootlegs now unfortunately. If it's a low starting price with no reserve it's most likely a boot, especially when the seller points out a lack of the too-hard-to-duplicate insert (e.g. ebay)

What I really love is those bootleg listings that say they are sealed copies, but no insert - if it's sealed how do they know it hasn't got an insert (unless they "sealed" it themselves)?

never thought about that one!

If you are going to sell it make sure that you go out of your way to mention that this is a Legit US Region 1 release and not the bootleg version that is rampant on Ebay. Also be able to prove it with detailed pictures of the dvd and case and insert of the actual dvd. Otherwise you probably won't get the max amount that you could get for it.