Vistaprint offers a Custom-Printed T-Shirt
bundled with a $5 credit on a future purchase
for shipping. (The credit will be noted during checkout. You'll receive an email detailing how to redeem the credit.) That beats our mention from last week (which didn't include the credit) and is the best deal we've seen for a custom T-shirt. Only front printing is included in the price; additional customization is available for an extra cost. It's available in sizes from S to XL.
Of note, XXL costs an additional $1.99.