Quality of bootlegs in most cases is slightly to vastly inferior to that of the official version. Not to mention, apart from the fact that purchasing from pirates is wrong [you're rewarding crooks, who think it's not okay for Paramount or whoever to make money, but okay for them to do so], it has been argued that pirate sales increase the cost of the legitimate product.
Try half.com, try your local EB or Gamestop stores used sections, try dvdpricesearch.com. If somethings too expensive to buy, don't buy it, or look for a deal, but don't buy a crooked product.
Signals I look for:
* Chinese subtitles or text on the box
* region free
* far fewer disks than the official release
* overseas seller
* no actual picture of the item.
You can also find legitimate non-R1 versions/import versions of a release, if you have an multiregion player. The 'morality'/legality of buying those in the US is questionable, but it's a whole lot better than buying a pirate version. At least you're buying an official version, just an 'imported' version.