From the new T&C:
Quote:
6. You May Only Have Five Accounts Because Your Pets Need Your Attention. It is important that Neopets users are responsible for their pets and play the game in a fair manner. Therefore, do not create more accounts or Neopets than you can maintain. You are allowed a maximum of five (5) accounts. One of these accounts, your main account, can do everything on Neopets. The other four accounts (except if one is a guild account as explained below) can adopt Neopets and maintain a gallery but cannot have a store, play games or any other activity that earns Neopoints or participate in any voting activities. You may freely transfer items among your accounts but they should be on the same e-mail address as your main account. If you are the head of a guild, you may use one of your five accounts as a guild account and it should be named as such (for example, Abandoned Computer Chips Orphanage guild account). In addition to your main account, a guild account can have a store but cannot earn Neopoints in any manner other than through the store, auctions and trades (and anything that happens on that account could impact your other accounts). If you maintain a guild account, you will be held responsible for that account. You are permitted only one guild account per guild.
I bolded the part that I think pertains to your question. The short answer is No, you can't have a shop on other accounts, only on your main account (unless it's specifically a guild account).