That was useful.Will try to stick to direct drive.
What could be a reasonable price for a decent vintage tt?Is it possible for around Rs 7,8 k?
My take based on a bit of research which I did for myself:
Garrard Idlers, Laboratory Series Turntables (not record changers):
1) excellent condition: Rs.7k to Rs.9k
2) fair condition: Rs.3K to Rs.5K
3) soiled/poor condition: Rs.500 to Rs.1.5K
Garrard 301/401/Zero, etc do not fall in this price range and are very expensive and much sort after
Garrard Record Changers
1) excellent condition: Rs.4k to Rs.5k
2) fair condition: Rs.1.5k to Rs. 2.5k
3) soiled/poor condition: stay away, not worth it
Belt Drivers, the modern plastic ones
1) excellent condition: not more than 5k
2) fair condition: not more than 3k
3) soiled/poor condition: stay away, not worth it as these are use and throw-away types
I would price these low as these cost between $25 and $100 in the United States (either new or pre-used). A lot of these turntables doing the rounds in India have been hand-carried by IT professioinals from the US. Ignore market conditions in India when you buy.
Vintage Indian Turntables - HMV, Philips, Cosmic, Sonodyne
Buy only if in excellent condition for between Rs.500 to Rs.3k depending on make. Avoid if the condition is fair or poor. HMV and Philips would be priced below Rs.1500 definitely.
Direct Drivers (Vintage): Technics/Pioneer/Sony/Denon/JVC etc
excellent: from Rs.7k to as high as Rs.13k (the exception being Technics SL1200 series and SP series)
fair: from Rs.4k to Rs.6.5k
poor: from Rs.1.5k to Rs.3k provided it is restorable
This is purely my opinion based on what i've come across from both a buyer's perspective and a seller's perspective. An excellent turntable would be in excellent cosmetic and functional shape, complete with magnetic cargtridge (atleast MM) and good stylus. It would also be probably a single owner turntable with traceable ownership history. A fair turntable may or may not have a cart but will be in fair cosmetic shape with minor nicks and dings. Mechanically, they should be fully functional. Poor/Soiled stuff would be in very poor shape, cosmetically and functionally and would need a lot of restoration work.
I have left out a few types intentionally as prices could vary big time and are difficult to predict as they are on the high side. A few of the vintage turntables from Lenco, Linn and models like Garrard 301/401, Thorens TD124/TD135, Technics SL1200, Technics SP10/15/25 and EMT 938 turntables fall in this category.
Hope this helps. Again, this is purely my opinion.
Edit: Also a lot depends on luck and your destiny. You may have a relative (close or distant) who may have this wonderful TT packed up and lying in the store room or loft. You may just about get it for nothing

I remember as a kid in the late 1970s and early 1980s, most upwardly mobile kerala homes used to have these japanese hi-fi racks (brought from the middle east), populated with gear from Sony, Pioneer, Technics, Panasonic, Akai, Sansui and more...a TT was usually part of these racks. There should be a lot of these stored all over the place, not in use. If you are after these, happy hunting!!