I managed to find some canvas bags for the bargain price of 50p (about a dollar for my US readers) and decided with a bit of applique they would sell well. So far I've sold 3 and got a few people interested in one too so I'm happy.
Here are the custom orders I've made so far:
This one was for a car mad little boy called Ethan.
Apparently all three children loved them!
I've also made a start on a few non personalised ones for the upcoming spring and summer sales: