This website are running an offer atm, they produce custom T-shirts and at the momment they are selling white T-shirts with one A3 size image on for £2.95
http://www.streetshirts.co.uk/tshirtprinting/
Thats the link to the promotional code. (it changes every hour)
http://www.streetshirts.co.uk/creation.aspx
Thats the link to the T-shirt designer
And here is the design I used:

its a large image so should be fine to use

I hope it works for you!