How to prevent ppl from buying...

I noticed some Mushie shops have items for Max and nothing else sold and when you try to buy it with max meso's it says the buyer doesn't have enough Meso's o_o

If they sold an item in their shop, then had max mesos when they tried to clean out their shop, it removes the sold item but leaves the mesos in the shop so they can put up more items and not need to sell something to make sure no one can buy their max mesos items.