I have been successfully selling t-shirts for over 10 years and have been in a similar situation. I would recommend selling the t-shirts for $4.45 each. This assumes you are paying about $2 for the shirt delivered to you, if you pay more add a few cents to the sell price. This will give you a gross profit of about $3675. Subtract labor ($300 - $400) and materials ($100) and you will end up with about $3000 dollars in net profit, not bad for 2 days of work on the manual.
If you price it out much higher than this, the customer will shop around, and the bigger guys with the autos will beat you out. Don't even give them a reason to look if you want the job. Also, customers purchasing this quantity don't pay screens or art charges, unless the artwork is in real bad shape.
Some tips to save money:
1. Try delta shirts if the customer will let you, they are on special for about $1.60 for colors delivered right now and compare nicely to the Gildan. Just because you pay less, does not mean you have to charge less!
2. Get your hands on a 1 color press and ask for some help. Lets say a 1 color press costs $250 used on ebay, you can add a person at the end of your oven and print the fronts, while printing the back.
Hope this helps!