Kevin Roth of Klamath Falls, Oregon, proprietor of Arms To Bear Security Services, posted an online advertisement for a firearm sale on the site Gunbroker.com. In the advertisement, it was clearly established that the seller did not collect taxes or fees, and that USPS Priority was an available shipping option. I clicked the "Buy It Now" button on the site, then contacted him via email to tell him I would be paying by money order, would like the cheapest shipping option possible (which was USPS Priority), and would need an invoice for the total costs.
When I received the invoice, he had added his seller's fee, and had invoiced me for UPS Ground, which was about twice as expensive as USPS Priority. When I complained about the added fee and the more expensive shipping, he 1) indicated he no longer shipped via USPS because of a bad experience with them, despite having listed USPS in his ad; and 2) insisted that the auction "clearly stated" that the seller's fee would be added to the final list price (he had a mention of the fee in the item description which indicated his prices included Cost + 10% + listing fee, which to me was an indication of his commitment to keeping the selling price as low as possible, not an indication that there would be an additional fee on top of the list price).
When I pointed out that the auction was anything but "clear", given that the listing had contradictory and ambiguous wording, and refused to pay the fees, he tried to gaslight and bully me into paying anyway, insisting it was my fault for not contacting him before clicking the buy button, even though I had no idea he was going to add an undisclosed fee, and never once had a seller try to get me to pay their listing fee after having bought several items on the site in previous months. When I refused to pay, he complained to gunbroker.com, and they apparently took his side in the matter; I tried to contact them to request support, but only ever received terse responses from them which didn't address my concerns, and when he filed negative feedback on my profile, and I responded in kind on his profile, within 12 hours gunbroker had deleted the feedback I had written.