Well, for what it's worth, here's my opinion:
We agreed to go by Cigar.com prices if they carry the cigar you're wanting to take or put.
If they do not carry the cigar then I would check other web sites (JR's, CI, Famous, etc.) and see if they listed a MSRP and use that. If all they have is a box price then divide it out to get a single price.
If it is a cigar that has a rarity factor to it, ask for opinions. The main objective is to be as fair as possible to everyone without tying up a lot of time.