I've never had it done but several posters have recommended powder coating. Prices they have quoted start at about $75.00 and up for stripping and one color powder coating. That's pretty cheap. I'd make sure they know to mask off the bottom bracket threads and the inside of the head tube and seat tube.
To strip and paint it yourself paint stripper and related materials, primer, sand paper, and paint are going to cost at least half that much money. If you use rattle cans you probably aren't going to get as professional looking outcome either.