My girlfriend's a screen printer (yayldn.com or @yay_ldn on Insta) and reckons that she'd come in a bit below this handscreening them in Hackney. Minimum run would need to be 25. Send me a DM if you're interested and she can work out an exact price based on the types of tees you want etc
Let's see how much interest there is. I would also want to find out who originally came up with the design, and get their permission to reproduce it. Would hate to suffer the indignation of designers 'on here'.
Last time I did this (about 3 years ago), it worked out about £13.50 per shirt.
At a rough guess, I'd say £15.00 per shirt to cover for inflation. (+£1.50 postage).