There are like, what; over 300 types of items constantly bought and sold within Pronteras markets?
Its not impossible but extremely difficult to update each and every one of those items every day. This is not including those less common items that enter the market once in awhile and are either extremely rare or have little to no use.
Your choice though, a sincere good luck with it.
Though if the item is not for sale in pc.bot.nu, chances are the person won't find it for sale.
I've always believed in those who overpay for a certain item to have deserved it. Its not the sellers fault that the buyer has no clue on the prices of the item he or she is buying.