This is an entertaining thread. Went from bashing JHS to bashing the OP. Seems like both sides are overreacting IMO. Seller can do what they want with their cards. Buyer can choose to not buy if they don't like the terms.
I'm fully aware that JHS is tough on offers, (I think I've had one accepted in around 20), but he also is already one of the lower pricers on the site. Are those prices still too high on some cards? Sure, they might be. OTOH, some might be too low. In the OP's example, JHS simply thinks his price was too low after the offer alerted him to check.
There's nothing wrong with changing a price when an offer alerts the seller that their price is too low. I've done it a few times myself. Although I'll give the offerer a chance at the old price in my counter, even though I wouldn't consider that a requirement of all sellers. Your protection from the chance that the price gets raised is to just buy the card at the list price.
I don't know if I speak for all COMC sellers with this statement I'm going to throw out to buyers: Low end ONE-card offers (under $1) are kind of cheap (annoying/insulting). Do you really need to haggle over a quarter?
Sidenote: I do like the OP's attitude/humor. If you do find that Harrington 1/1, I'll give you $4 for it. I can probably get $5 for it here in Portland.
I collect all Oregon State alumni.