domain railkhana/com Buyers interested. What price should I set?

Hi guys,

I bought the domain railkhana/com (In india, 'khana' means food) last month and I contacted a few websites in the food catering service for trains in India. They've showed interest in buying the domain but we haven't talked about the price yet. So I'm wondering what the right price would be for this domain as I don't have much experience in domaining and never sold a domain before. Please share your insights.

Thanks!