The problem is a general sloppy lack of coherence. In one episode Jake has no money to buy his dad a gift (because the federation doesn't use money) but then Sisko buys a rather sizeable piece of land on Bajor (which must have cost a lot of money). So either Sisko has been doing some trafficking on the side or there is something really wrong here.
I'd assume Starfleet officers get a stipend in whatever local currency they may be likely to encounter. Ben may give Jake a few Bajoran coins or a latinum strip for some jumja sticks, but not enough to buy 400 year old merchandise at auction.