can you answer the below questions?
- do you have an office? how much does it cost to rent?
- how much for your internet connection?
- do you have any other staff? if yes, how about their salary?
- how many sales per month do you think you will get? which payment method will you use? how much does it cost to process per transaction?

etc.

It's not only in hosting reseller business, but also in any business. You will need to calculate your fee, then % for profit, then you can have the price