Plus you get a bag of sweets to "sweeten" the deal :p
I have quite literally dozens of qwertee t-shirts. The only times I have retired a qwertee is when I have somehow damaged it (poked a hole in it, got paint or something else on it). They are really good quality. I agree that the postage taking a while can be annoying but part of that time is to allow them to actually print the t-shirts
As I said, I've never had issues with the quality. On the one time my delivery didn't arrive, qwertee responded quickly, and sent another batch out, and said if the original delivery turned up, we could keep them. So all in all, we were happy with their response.
I bought 10 last time they had 50% discount and I was very disappointed. The quality of fabric and printing very bad, I tried to contact them to return some as they even sent few random when they were out of stock after I purchased as in stock. Also they post from Ireland which is not very clear that it may take up to 15 days to receive. Luckily I paid by PayPal and got full refund as they never responded to the claim. Never ever for me..
I've not had any problems with any of mine - had about 15 over the past few years. All of mine are Gildan branded, which seem to be the brand of choice for official merchandise, both at events, and in places like HMV. Postage does increase according to number ordered, but if you sign up for e-mails, you get £1 off your order (every order - as you get a code every day), and they do frequent sales and special offers. The happy hour doesn't seem to run every day though.