Most signed shirt are not expensive. You can for example get a signed shirt from a living legend like Robbie Fowler for a reasonable price. But a signed shirt that just hangs on a hanger is not very attractive, so you'll need a frame. A frame that doesn't look cheap and has a structure to present shirt could add significantly  to the price, depending on what you are willing to spend.

Here are some factors that will determine the price of signed memorabilia: