A couple of things I can think of…
Used guns are difficult to compare against one another, especially if we don’t know what the two guns are or have pictures. Was the other seller a business? It’s generally safer to buy from a business than from a private party.
The other gun could have been in better condition, or honestly even if it wasn’t it could have had better pictures accurately showing the condition. I would much rather buy a gun with more wear that I could see and judge versus a gun that has one blurry photo and a seller who promises it is in perfect condition.
Again, depending on the gun, it could have included accessories. Nobody is spending extra money because a gun comes with a holster, but mags can help sometimes. For example if you’re selling a Glock where new mags are $25, people won’t get too excited about an extra mag or two. But if you’re selling a P7 where mags can be $100 or more, 3-4 extra mags included with the gun can help.
Finally, if you wrote the for sale ad like you wrote the OP, I’m not surprised you didn’t get bids. No it’s not fair to non-native speakers, but there are enough scammers who write in broken English that it turns into a red flag for a lot of people when they’re buying second hand. For a final price difference of $35 I would absolutely be bidding on a gun with a description that was well written.