Got to put in my choices...
1) Wing Commander (just check out RottenTomatoes for the ratings on that turkey!)
2)Battle Beyond the Stars (George Peppard as a space cowboy?)
and finally
3)The Black Hole (when you have star power in the form of Ernest Borgnine, and you still can't make the movie exciting...)
Sorry , have to invoke the 'too hard to get' clause on Battle Beyond the Stars. Indeed I think it is prime material but it is out of print, not available on Amazon (directly, only used copies like ebay and WAY expensive at that) and of course not likely to be lying around in your local video store. I would love it since I already have a copy and all, but too obscure.
The Black Hole is more likely to be on video shelves, available from Amazon directly, and Disney related so it is likely to be on more shelves altogether.