How to prevent ppl from buying...

...your max mesos priced item in your store? Do you just need to have 1 mesos in your inventory or is it something like 50m because of the tade fee?

Selling a max meso+ item for the first time x3

You can also put items up for 1 meso while holding the max amount in your inventory to prevent people from buying. I remember some guy did that with a pair of Face Stompers back when they were worth well over 100 mil (or something like that).