I repair and service valve amplifiers. Mainly guitar amps although I do the occasional Hifi.
I don't charge just to have a look. I don't charge if I can't fix it (although I can't remember the last time that happened). I charge for parts at cost.
I can generally turn stuff round in under a week, but if its urgent and you're prepared to pay I can do it quicker.
I occasionally have amps to sell.