Hi I have a toshiba 50h82 tv that is 7 years old

You are describing 2 different problems. The convergence problem can be fixed by either resoldering the convergence ICs or replacing them. These ICs cost about $25 each and there are 2. I suspect that the $4oo is for replacing the convergence board. This should not be necessary as the board can be fixed. Also, the brightness problem can be dirty CRTs, dirty mirror or faulty coolant fluid on the CRTs. If the picture was good prior to the convergence problem, the set is probably worth the repair if you can get the board fixed. While the board is being repaired, the service shop should be able to tell whether or not the brightness can be adjusted.

Dan