Looks very good for me.
I have actually emailed them an enquiry of my own - do they only do images or is text only possible.
If so, i will probably give them a try.
The free delivery option is quite slow, but for free you can't complain too much.
This is a very similar thing to what myself and a friend were looking for quite some time ago. Maybe we might look into it again.
approx £1.50 for a custom designed t-shirt and delivery is pretty darn good and a damn site cheaper than my local t-shirt printing business wanted per item.
And another plus thing - there should be no import & taxes to pay.