A word on logos
If you have a fan base of tens of thousands of people you might be able to sell logo items otherwise ...
Sometimes I feel like asking "Who do you think you are?" I don't put that way because it would be misunderstood. This reaction comes when checking a shop after hearing the "Why am I not making any sales" cry. I look at the shop. The first (and very often only) design for sale is one that very obviously and prominently advertises that shop, or perhaps the shop owners other website, a club or some small group. That will explain the problem right there. Customers want to see stuff for them, not for you. They want designs that speak for them, help them express themselves, reflect their beliefs and values, or are just fun or pretty. Chances that someone is going to pay you to advertise for you are very small. If your logo or advertisement is very cute or very cool you might sell a couple a year. But you will have turned away all the customers who would have bought coolness or cuteness if that advertising did not exist. When someone arrives at your shop the very first thing they should see is something that is about them or for them.
Now there is nothing wrong with logo items. Using a POD to make logo items available to club members is a great way to avoid order taking, inventory, arguments about which kind of apparel type to choose etc. Logo items for you (or your friends) to wear can be effective, but rarely as effective as wearing an actual really cool design that makes someone go "Oh, where did you get that?" For the most part, however, nothing on the item for sale should have an obvious advertisement to the maker. An inconspicious url worked tastefully into the design or resting quietly in a corner will usually not be objectionable. Ask a someone to view the design, then take it away. Ask if they noticed the URL. If they did, then it is too prominent. If they did not, that is exactly the way you want it. You want it there, but unnoticed unless looked for.
It is true that people will pay to buy stuff with company logos on it. But those companies have spent millions of dollars creating an image for their stuff. When you have spent at least several hundred thousand dollars creating a sense of coolness about your entire line of products then maybe you can get someone to buy your logo wear. If you haven't got that kind of advertising budget stick that logo item in a corner someplace and showcase your art, your humor, your wit and your insight.