I don't remember if this site was posted in here. It's RTS Vapes:
http://www.rtsvapes.com/default.asp
If you want to mix up your own liquid they have everything. PG, VG, liquid nicotine of various strengths and concentrated flavor liquids. If you do this be very, very careful with the liquid nicotine. Don't let it come in contact with you as you mix your juice because you will absorb it and overdose through your skin. They sell PPE (Personal Protective Equipment) as well:
http://www.rtsvapes.com/Laboratory_S...pment_s/53.htm
And provide a link to a forum where best mixing practices are discussed:
http://www.e-cigarette-forum.com/forum/diy-e-liquid/