The beautifully remastered 15th Anniversary edition of Eric Chahi's cinematic side-scroller is available from GOG right now for $3.99 as part of a 24-hour sale. It'll return to its normal $10 price tomorrow at 6AM EDT.
This sale is a "GOG Gems" promotion -- the retailer offers a deep discount on a catalog item every third Wednesday, with the stated effort of introducing players to classics they may not have played yet. GOG refers to it as a "curated promo."
Oh, and while you've got your credit card out -- Star Control 1 and 2 are on GOG in a $6 bundle. If you've never played either, then you're missing out on not only a great strategic experience, but awesome spaceship combat as well.