I am planning to build a house and the standard a/c and furnace is 13 seer carrier with a 80% efficiency furnace. To upgrade to a 14 seer carrier and 90% efficiency furnace its about $1400. I plan to live in the house at least 10 years. Is this a good investment to save over the long run with more efficient a/c and furnace? I live in Oklahoma if that helps. :D

I would say to make the investment and get the 90% 14 seer. The cost of energy is going up and up. Also you may be able to skip the cost of a chimney with the 90%. Most of them vent and intake via 4" PVC through the wall.

Ballenger is correct. Would be a good investment

Not much difference between 13,14 seer ,but will help when you sale to have the 14 seer .90% heat is good up north but not worth it in warmer climate