Before comparing with the rest of India, I’d solve the Delhi sample first. National comparisons can hide local differences in buyer pool and transaction process. A neighbourhood-level set of completed sales is more useful than a broad claim that the whole country matches.
For the rental side, work backwards from the rent you can support, not from the seller’s asking price. Include the purchase amount, transaction and updating costs, recurring building charges, maintenance, vacancy and any furnishing needed. If the deal only produces an acceptable yield using an...