I am looking for the best process to make custom shirts. I am going to
be ordering about 300 custom shirts and I want to make sure they are
made with the best long lasting quality. What type of questions should
I ask whoever is making them? What type of inks are best. Is silk
screening the best way to go? And what am I looking at per shirt for
for that quantity. Any known good online companies? Any big difference
with going with multiple colors?

In my former life I ordered through Lands End and was extreemly
pleased. Can't beat their quality. I especially liked being able to
order Womens sizes. Typically club or freebie T-shirts are all just
distributed in Extra Large. Our group especially the women liked being
asked what size they wanted and being able to get clothing for women
int he right size.

10 years later the Land's End clothing still looks great. BTW one item
I remember that was a big hit was their oford button down shirts. Good
Luck to you.

http://www.cafepress.com/cp/info/

I have purchased a few shirts from different venders.  you can design
your own shirts, and either make a huge order, or sell them directly
from the store they will set up for you.  they make a base price for
the shirts, and you can tack on how much extra you want to make.