There is a lot of competition in dog clothing stores anymore, so you need to be prepared for that. There are dog clothing patterns you can buy at fabric stores like JoAnn's or even Wal-Mart. I've made most of my patterns, after getting the basic dress design the way I wanted.
Just to get started you could try to make a few things to sell here on YT (you'll need to be a donating member first). See how successful you are with sales and go from there.
Most members here that sell do accept paypal and don't have to be set up with cc services or a shopping cart service to accept payments.
Good luck with your new idea!
