A lot of auctions don’t see much action until the last few hours. Ripros pretty regularly go in the 300k range, even if you don’t bother to advertise them. I think a lot of people only really pay attention to the files that are ending fairly soon.

Really, two things affect auction price: Utility and Rarity. Ripro is one of the very best files in the game, but is very very common for a file that good, so it costs less than it otherwise would.