Hide shipments for other classes that can't purchase? DarkRP

Hello,

Right now in my server, gun dealers are the only class that can buy guns in the F4 menu, but currently, all other classes can see the guns, but when they try to buy them, it says /buy has been disabled. I want to know how I can disable other classes from seeing shipments that they can’t purchase. This is probably something simple I missed, but I can’t figure it out. And yes, I have googled til I couldn’t google anymore, looked in a bunch of files, all to no avail. If anyone has an answer, it would be much appreciated.

Thanks.