Amazon currently has the Star Trek (Single-Disc Edition) on sale for only $3.50 and the Star Trek (Two-Disc Edition) on sale for only $6.22! There are extras on both, so take a look!
Any prices listed in this post are current as of the post time. Prices at Amazon can flip fast, so don’t wait too long if you’re interested! When you’re done here, be sure to visit my Amazon section for all the best Amazon deals!
(Thanks Mashup Mom!)