Wow, I thought it was only $20 for the battlechest.
I would just pirate it unless you want to play on Battle.net. Even if you aren't that tech savvy, there isn't much to it with these older games. Mount the .iso in DAEMON Tools, copy/paste the serial, install, and you're good to go.
Then again, if you aren't a filthy poor like me I guess $40 isn't shit.