I just realised you could get good cheap soldering irons by making a box that measures the resistance of the heating element and TRIACs them for temp control. In order for the iron to heat up nice and quickly you'd get 110V irons and run them at 220V, because you're measuring their temperature via the element resistance there's no risk of the element burning out. It would mainly be useful in 220V countries, but I guess it also works where you've got 2x110V sockets like for a welder.
Bet you could make such a box for like $25.