From my limited experience I've always been under the impression that over putting is acceptable. Not everyone can match a cigar exactly rarity for rarity and price for price, but I like someone I spoke with today said "I'd trade a $8 cigar I've never had before and I want, for one of my $12 cigars that I have stock piled any day!"
The way I do my pricing (which isn't how I'm telling you to do yours, nor am I saying it's right) is to find multiple prices from a couple different locations and average them out. Just a example of my logic would be if you found 3 prices on the same box at $145, $150, and $155, I'd say the average price is $150 a box. I would however not include a price in my equation if say the box was on sale for $50 less than everywhere else. That would then make a $5 cigar average out to maybe $3.87 a cigar. Once again, I'm not saying that's how you should do it, that's just my logic on the matter.
If you want a $16 Feral Flying Pig and propose trading one of your many Padron 85ths at $20 then that is your choice and that would be acceptable by most of us.