[patio11]

Having some accidental knowledge of this market:

1) Professional speech therapy is surprisingly inexpensive and mostly sold to parents, who mostly pay out of pocket (as opposed to via insurance, even though it is semi-medical).

2) Lots of professionals pay for accent coaching / accent modification, which can be accomplished by someone with patience, a good ear, good rapport, and no expensive degree. This is a good part-time job for people with an "in" in a particular foreign community, by the way. (I'm personally aware of Japanese executives who spend $X00 an hour for it. Cheap at the price if it gets you the promotion, right?)

3) Professional translators would suggest shadowing, which is taking source material (like a news program, video, etc) and just trying to reproduce it exactly like the original in real time. This is maddeningly difficult the first several times you do it, but you will get better really quickly. (I tape myself doing it, which is useful if you want to get e.g. native feedback or just have a record of progress.)

[thenomad]

Shadowing works remarkably well. When I'm doing voice acting for a film (or indeed, GMing a roleplaying game) and I need an accent I suck at, it's the most effective technique I've found for rapidly improving the quality of my accent.