They don't just take an eraser to your skin and rub the tattoo off. Getting that much ink off would probably take a year or more and I can't even imagine the cost and the pain. And it never really comes off. I've seen tons of tattoo that were lasered "off" and you can still see them. $2,000 for that much work is a bargain, particularly since it's good work.
Finish the sleeve and do better on the next one. You only think you're unhappy now. By the time you get through mucking with that arm, you'll probably have $10,000 in it and be REALLY unhappy with the way it looks. Not to beat up on you, but this is why you think BEFORE you get a tattoo.