Thinking about getting back into WoW

After about 3-4 years I'm thinking about getting back into WoW. I could really use a game and WoW really appealed to me.

I noticed they've raised the max level to 100. Is it worth starting from scratch or should I buy an account? I want a human priest this time on an EU realm. Not sure what I'd have to pay for that or what the risk is with getting banned etc.

Just after some advice right now. I need to buy a gameworthy computer before I actually get an account.

James