Up to you where you play.
But Private Servers are against the EULA/ToS, so we don't really want them discussed here.
The admins try to keep everything legitimate and within the rules.

Warcraft has been around for 5 years.
And is probably currently the best game in the genre as well as the best for that entire period.
Nothing is the top forever, but nothing is close to warcraft as of yet.

Boxing isn't really that cheap of an activity.
But its a lot cheaper then many others.
The initial investment per account, and the infrequent expansions all add up to a bit.
But its a lot cheaper of a hobby then a lot of others.
We definitely get our money's worth.