How much will I have to spend on a decent 600-700m range vtx and a receiver...
Do I need to buy goggles...or can a airplane be flown just by looking at a screen..is it practical??
I have a runcam 2( yes latency isn't too good for fpv but...)... I need to see what it's doing...am on a budget.....
Used parts for sale are also welcome...

A 200mw receiver should be enough for 600-700m range.   You can order Eachine TX526 200-600mw switchable VTX or any other brand.  Price should be Rs.700+

As far as receiver is concerned there are two options
1) FPV goggles (almost all of them come with in-built receiver)
2) OTG receiver for your smartphone e.g. Eachine ROTG01

I prefer FPV goggles because you can concentrate well with them.  Go with OTG receiver if you feel dizzy with goggles.

U could get a screen for like 900 rs and screen is almost as good as a goggle as long as u don't want an immersive experience. And the 600mw txs get hot quickly but has a good range.

It should cost near around 2000-3000 INR!

Gonna have to wait a month to get these...
..ah...
Hopefully fpv is a lot of fun.