I have a business class flight on Lufthansa from SFO to DEL this December, and would like to purchase baggage insurance for my return flight, to cover my valuable wedding shopping I know Lufthansa does not offer insurance - does anybody know where and how to purchase reasonable insurance?

Thank you!

If you have coverage for personal property in your home, it may also cover you on the road. Check you policy or ask your insurance agent about adding to that policy for the coverage you need.
For travel insurance, look at induremytrip.com for comparison of multiple offerings from a dozen or so carriers.

That's insuremytrip.com, of course.

Just shows how different things are on this side of the pond - most people would have travel insurance to cover lost luggage / delays / medical expenses / repatriation if they were going on a trip