If you want a store ready to go. I designed the t-shirts etc and am using a service where people buy the item, it gets printed and shipped. This is all set up. So there is no stock holding so very low risk.
How can the future owner improve the business?
You can improve the business if you have time to invest in marketing and getting more products from wholesalers.
What work have you put into the store?
design and design of the items.
How many hours does it take to run this business per week?