The trick to a bicycle wheel isn't to eliminate wobble from the rim, it's to have all of the spokes as evenly tensioned as possible. My guess is that your's aren't, and the fiddling your bike mechanic has done has imbalanced them more.

I'm thinking that your most economical choice at this point is to buy a whole new wheel set. You could have your current hubs rebuilt but, with your history of broken spokes, your rims probably have a terminal warp. New rims, all new spokes and the labor to relace your wheels will exceed the cost of an equivalent quality wheel set.

Oh - and that story about black spokes being significantly more prone to breakage is baloney!