this maybe worth considering ultrafire c3

stainless steel version 1 x aa $20.90

http://www.dealextreme.com/details.dx/sku.11133

lasts about 90 minutes on an eneloop 2000 bloody good light i have 2 of them and 2 more on order

aluminum version 1 x aa $16.86

http://www.dealextreme.com/details.dx/sku.1993

here is a review of the 1 x aa http://www.light-reviews.com/uf_c3/review.html

i have 7 of these

aluminum version 2 x aa $19.41

http://www.dealextreme.com/details.dx/sku.4452

with the 2 x aa runtime is about 4 hours

there are other versions that are multi mode or use the q5 led.
q5 model draws more power and has a runtime of about 60 minutes with an eneloop 2000

here is a review of the multi mode version
http://www.light-reviews.com/uf_c3_5mode/review.html