it depends what kind of music you are looking for. I don't think a single person here can get you all the details of availability of Indian/western classical, bollywood,philharmonic,trance/ambience,jazz,rock,metal.......
whats your taste? I am in bollywood (hindi film OST), hopefully I will be able to help you in this category, there are a few members here with fantastic knowledge about other genres
My general suggestion:
1.Slowly learn to judge quality of an used record just seeing under sunlight.
2.Look around, discuss, search, read: it takes time to evaluate price of a record, its easy to get duped if purchased in haste and over enthusiasm. I have learned this hard way.
3.Observe different records: see the density,distribution of grooves, try to distinguish between a mono and a multi track stereo record, by looking at it its not difficult to predict the fidelity its going to give you.
4.Wait for the good condition records, don't buy an average condition record with the hope that record cleaners will do the job.
5.Majority of indian used records were played with ceramic cartridges, stay away from scratchy records
6.Prepare a plan (homework) what you are going to buy and when
Just remember majority of records are still available- all that is needed is patience and sustained efforts. Don't leave a fabulous record even of you have a copy, records have extraordinary resale value.
go ahead, make the best of this wonderful media
Oh yes start visiting Wellington square and have a friendly relation with those guys - records are no more pressed, they need to be found out from wherever they are lying