I have a decent setup that I put together for a friend. I think its around $70-80 depending on where you get it and shipping.
Its a decent starter kit that I used for a long time. Here are the links to the parts, but not necessarily where you should buy from. Shop around for the best price.
http://www.smoktech.com/product_10053.html
http://www.kangeronline.com/products/aerotank-mow-emow-clearomizer?variant=883975493
http://www.myvaporstore.com/Joyetech-eGo-Rapid-USB-Charger-p/ego-char.htm (omething like this, any "ego charger" will work)
From there you'll need to order "ejuice" to refill it. Do you smoke right now?
That's an upper end starter kit. If you wanted something a little bit more you'd be looking around $100 for the box, $40 for the tank, $30 for batteries, $25 for a charger, and $13 for juice. I could make recommendations for that too, but its a step up.
Same here, but once I saw that kit with everything together I couldn't resist giving it a shot