I printed out around 500 shirts for school this past term and used this company:
Email:
info@arteescreenprint.com
Toll Free: 1-888-848-6066.
For blank tees and products, please visit us at T-shirttown.com
100 Fruit of the Loom Heavy Tees (White) printed with 1 colour - $3.75 per shirt (add $0.50 for coloured shirt*)
100 American Apparel Unisex Jersey Tees (White) printed with 1 colour - $7.50 per shirt (add $1.00 for coloured shirt)*
*20 setup fee not included
Artee Screenprint & Embroidery
37 West 7th Avenue
Vancouver, BC, Canada
V5Y 1L4
They had the best price around.. I'm not too sure how 'high' quality you are looking for but the shirts that I have have been washed and worn many times already and are still looking fine