If you want high quality posters, I suggest Cloudy Dream. The owner, -Melie only takes a few slots at a time, so when she is open, you have to hurry because the spots fill up FAST.
http://www.asianfanfics.com/story/view/447679/cloudy-dream-poster-request-shop-open-request-now-graphics-poster-request-postershop-graphicshop

You can request at the shop I had requested most of my posters from. First, subscribe here to know when your poster is ready:
http://www.asianfanfics.com/story/view/742902/fly-to-love-graphicshop-open-graphic-poster-request-postershop-requestshop-graphicshop-hiringdesigner
and then fill in this form http://www.tfaforms.com/332268
with all your information and then submit and go back to the main page of shop to let her now that you had submitted a form. She'll get back to you soon since the shop is open now.
Good luck ^^