Buy a divx player and you can play anything, here's one for 29.00:
Or you can get them for even cheaper in Aldi at times. OR you can do like I do and accumulate dvd players from the op shop where they are about 5.00.
And then you buy your Star Trek from dvd.co.uk which is almost always dramatically cheaper than buying it in Aus. Here's season 2 for £19.79 which at just over 30.00 Australian is a great price (postage from that site is very inexpensive too).
OR you make Star Trek friends IRL and get them to loan you the dvd's.
All of which I say because Mirror Mirror is a great ep, would definitely be my top 10 TOS episodes and my favorite MU ep. It's got everything.. drama, philosophy, shock, hotness.. it's a stand out IMHO. And classic TOS in every way.