Hi I need a laptop. But don't have the capacity to spend on a new one rn. Where can I find a good second hand laptop ?

Olx et al are honestly quite shady / anxiety inducing to me and I'd prefer offline or personal experienced recommendations.

What I am looking for / context

I don't have a steady base of operation so I'd prefer a light or rugged one.

I'm not in it for the fancies. I am fine with one or two generations behind. But I don't want to be stuck on an ancient one. I wish to use this for study and experimentation (cs/it related, self study) so want one that's relatively new enough to run things properly and support modern compute features.

Dents and scratches are no issue. I just want it to run solid and not flake or shatter with some rough use or travel related abuse.

I have been using an 8 year old one, for this. But it's showing it's age. And barely holds together. it's almost 10y from original release date.

TL;DR

where can I find a good one at second hand for cheap in Kolkata? How to go about it. And tips for not getting swindled with a bad piece. Thank you.

Budget is around 25k or lower. (more like 15 😓😥)