Are you talking about $20 atomizers? or full kits?
$20 atomizers is a bit high,even for the expencive ones.
I have seen them for as low as ten bucks each.
Over all the battery life is what it is. The only thing you can do about that is get a larger type of E-Cig, like a Pen, or Pipe, or Cigar which have larger batteries.
You could make your own battery pack, like the Magnum or a USB mod or USB battery pack mod pretty Cheap, but those are about the only options for better battery life.
The Battery tech is just not there, and the Nuclear Batterys were never approved because the public is just to stupid to use them

(there really is such a thing)
They do make Disposable cigars and Smokes, but for the prices, i dont think they are worth it yet. They are from 18-28 bucks each.
The newer Mini/Female pipe battery looks promising, but its still real new, dont know if it will be any better use time then the normal batteries.
A Starter kit Can be had for 30+ dollars or as low as 15, but normally, you get what you pay for with these, with VERY few exceptions, or unless you can find a real good Ebay deal on a 901 or Pen.