I took the plunge and did it myself and it turned out great. It took me only a few days instead of the many weeks it would have taken to send it to LA and back from Seattle.
Got some stainless steel buttons - not chromed steel. Turned out the diameter was the same as the installed plastic buttons, that was nice.
The old buttons were indeed glued on and I got them to release with a heat gun.
The tricky part was getting the height right. After experimenting to find the right thickness, I epoxied hardwood shims onto the bottom of steel buttons and then used titebond to glue wood to wood.
Once the old buttons were off, how would I know how to align the new ones? (I had the end piece of the finger board off, the part with the finger holes.) I tried making a paper template but that didn't really work because I had no way to clamp or tape the pieces in place while the glue dried. So in the end I just put the finger board back together and eyeballed the alignment using the existing holes. I had to tie the flappers shut so the buttons wouldn't sink into the holes when I taped them in place for glue to dry.
I was prepared to have to do it more than once if I didn't get the buttons placed just right. But it turned out great on the first try - how often does that happen?
Anyway, I'm really happy I did it. It took me many months to get used to the plastic buttons when I first got the accordion (my first box has the steel buttons.) I never really liked the slight dome shape they have. Every time I would switch between C and D box the difference would kind of bug me. Now they feel the same.