There was only one Target collaboration that I wish I'd purchased more from - more as collector's items than as wearable fashion. However, I have just not been that thrilled about most of the collaborations. I purchased some of the MIssoni housewares (the glass pieces) for my new kitchen, but the clothing wasn't anything special.
And it is interesting that EVERY. SINGLE. TIME. Target has a popular collaboration people complain about the resellers. Obviously Target either cannot or will not do anything about it. Of course, if you live in the Midwest like I do (where most people have never heard of the designers in question), there are never lines and they are never sold out. While I haven't made a trip to Target for this one, if this one is sold out it is likely only because the Today show said it was, so people around here went to take a look.
But like many people have already mentioned, most collaborations use cheap materials and the sizing tends to be odd. It sells because of the name (which, if we are honest, is often not terribly different from the full priced lines - different budgets, different "limited edition" playgrounds). Still and all, even not taking any collaborations into consideration, Target generally has better clothing than, say, K-Mart or Walmart or other discounters IMO.