The only time I've not made a sale for a customer that purchased on-line was:
1: My distributors did not have them in stock
2: A customer was not willing to wait for the requested firearm to come back into stock and paid more at another dealer than what I quoted.
Those were two separate customers requesting two different guns.
I have never lost a sale on price.
There have been times during my market research that online prices were below my dealer price though.