I do E-6 with the Tetenal 3-bath kit and it is cheaper than the lab, as long as I save up enough rolls to make a batch of sufficient size. I used to do C-41, and would say the same is true.

If you're not doing enough volume to make it worthwhile, try A&I mailers from www.aandi.com or B&H. If you order from A&I, you don't have to worry about B&H's minimum shipping cost, but if you order other things from B&H anyway, it may be more economical to get them from B&H.