Do not, repeat do not, buy a cheap Indian trombone. You're quite likely to receive something with a non-working slide. Or non-sealed joints. Ditto for other brass instruments. I don't really understand what's in it for anybody to produce such junk... It's as if someone just needs to go to the factory and say "Hey, do you realise that if you did these few extra simple things, you could clean up here rather than get a terrible reputation?", but nobody's done it yet... If budgetary constraints are severe, go to someone like Wessex Tubas, who have their manufacturing done at the Jinbao factory in China, but do their own QA and commission their own designs. Good trombones, many of them (always try before you buy if you can with anyone, even the top notch boutique makers). But there's always a certain amount of squaring with one's conscience the undercutting of more local workers involved when one goes for cheaper prices in this fashion.