If you haven't seen the front page of the Brickboard lately, a member in the 240 section has written a procedure to make the electrical portion of the ignition switch work again.
I did this many years ago and it is not hard. I just used an emory board to clean the contacts and electrical cleaner to clean up the dirt.

http://www.brickboard.com/RWD/volvo/1295954/220/240/260/280/used_old_ignition_switches_problems_refurbishment_switch_intermittent.html

Save $40 and a trip to the dealer. Unless the switch wobbles a lot, of course.

Klaus
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I still miss my 164 and my 854T. Just driving a V70R :)

Most switch contacts have a gold flash across them to reduce wear and tear. If it gets to the stage of having to clean the corrosion off the contacts, then it will wear even quicker for higher current circuits. However, if it is for low current, and the problem with the switch is just sulphidisation of the contacts, IE a build up of gunk, you might get away with switch cleaner alone. How long did the your switch last for Klaus after cleaning it?
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Tek

I only tried it once after I had already bought a new one. The old one did work, but has been sitting on my work bench ever since.

Klaus
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I still miss my 164 and my 854T. Just driving a V70R :)