Hi Steve,
That is a fantastic margin you are making on your printed design t-shirts. Any retailer would like to make a margin of 50 - 100%, so if you think the rrp would be $50 then you would have to be selling them to the retailer for $20-$25, each retailer will know their own clients and their likely spend, so they will have to dictate the RRP. Good luck with your business however i would presume many retailers would have already purchased their Christmas stock in advance. We are based in Sydney and are a graphic reseller company selling the DTG printer and inks, we have started a printing t-shirts as well and will in the new year be launching a webshop etc - so would like to pick your brain at some stage..
cheers