In binoculars more than anything you get what you pay for. I haven't used Pentax Binoculars but have heard they are okay. All things being equal, poro prism binoculars can be made of equal quality for cheaper price. What you sacrifice is compactability. I use Swarovski's and Leica's but I assume that's out of your price range. Nikon sells a couple lines of poro prism binoculars that are supposed to be of high quality.

If you are set on the Pentax I'd definitely take the more expensive version as I've never looked through binoculars where the price difference wasn't immidiately reckognizeable. Nothing beats looking through them either, if you can find a place that has immidiate long distance viewing or know somebody that has them I'd want to try them prior to purchasing.