Another vote for the machine shop. I was thinking that from the beginning of this thread. I think the one I went to charged me $25 to hot tank my heads.
Harbor Freight sells a parts washer for like $60-100 I think. My question is, what do you do with the solvents in the parts washer once you've used them a lot? I guess you'd take them to your local chemical collection place...we have one ran by the city, but you have to call and make an appointment first.