You can get a Joyetech Delta II for under $32 here with coupon code DNA10
I have heard really good things about this tank. I ordered on and I am going to try it out soon and tell you my impressions. You can see some of the RBA I use on the bottom of this page.
It is 22mm and comes with 2 replacement heads.
Can read more data about it and get it for $32 with coupon code DNA10 here.