Electrical - Wire NMB 12-2 (Internal)
http://www.lowes.com/pd_70111-295-28828269___?productId=1193433&pl=1&Ntt=12-2+romex $46.57. Then 5% with Lowes card ($44.24). Then 10% HomeDepot match ($39.82)
The price varies a lot with the world commodity price of copper, but about $78 for a 250 foot roll.
It is rated for 20 amps. It is the most common wire used in houses.