To echo what Bruce (sawman101), checking out the local supply stores may be to your benefit. When wiring my shop, I found the local electrical supply place must less expensive than Lowe's. Example would be in the wire: You buy it by the foot, but they base their price on a 1,000 ft roll, which is much better than Lowe's habit of charging you more per foot in the shorter quantities. As for the local lumber supply, the convenience of pulling my truck right next to the stack (which I can still hand select from which boards I want) is worth a few cents per board, as I have less labor and less scrap. Fastener supply places are also often cheaper than Lowe's if buying by the box.
Regarding local supply places, you may want to time your visit to when the contractor volume is down (i.e. mid-morning or mid-afternoon.) With less personnel, you may be in for a wait if there is a line of professionals ahead of you getting their supplies for the day, or for the afternoon work. Although stores like Lowe's are supposedly based on "convenience", I find it anything but convenient when they relocate 50% of their stock about once a quarter so you will see other "spot buy" items while looking for what you came there for. (Yeah, that is one of my pet peeves about them). The last thing I need is to have to look up and down the aisles (good luck with asking an "associate" where something has been moved to) for the one thing I need to move my project along.
Not saying I will stop using Lowe's, but they well may become the last place I go to instead of the first. And yes, as a veteran, that discount is the main reason I shop there in the first place.