Currently, the first ones to post offers get a priviledge: their offer stays high in the page.
I suggest, when the product is the same and the price is the same, offers are randomly placed each time a player search that offer or click product overview.
Why that? Example: people that put for sale at minimum first will probably get sold first, while the others might not sell. By the time it is first to sell, there is an update and the product updates price...
Adverts is the same thing: people put max price first and get supplied. Who comes later don't buy any. By the time they should be supplied, the product's price updates and people put highst price again.
Of course these anomalies will only be a problem when supply is bigger than demand in the market view and when supply is smaller than demand in the advert case. But it is still a problem.
Sure people that get online more often should have some advantadges, but being supplied more or being able to sell when others can't for same product/price should not be some of that advantadges.