Discogs. Alternatively, old records shop/dealer in your city. You probably know them already if you are a record collector.
If you aren’t insistent on vinyl, but open to explore CDs, then AIR and NCPA have a lot to their recordings available as CDs.
For one time listening and exploring, you’d find the following apps and platforms are dedicated to Indian classical music:
- Ragya
- HCL Music
- Saregama Classical
- Saarey Music
Also the following internet radio stations play only Hindustani classical 24x7:
- Shanti Shanti
- Sandesh Radio
- Sangeet Samvaad
Archive.org has many older Indian classical albums uploaded, some even in FLAC/WAV form that you can download and play through your computer/streamer.