I sent out flyers with "josh buys houses" on one side and a pizza coupon on the other. 

If I go to a museum and it has a QR code where I can get a $5 off coupon for the admission price I would use it.  

I have recently noticed when fellow investors or potential buyers send me properties lately they are usually off Zillow.Given what I see friends wives signing up for in the way of 'coupons', I would throw in an incentive (like a few $ towards a home inspection) if they sign up & then buy through you.

I apologize for the trouble you've had with the coupon codes.

Big one is saturation levels if urban,suburban,rural the ring radius changes.If you want to open a pizza place but in a 3 mile suburban radius there is 20 of them you are going to have a tough time out there making sales without running coupons all the time.An exception would be if you were the only Chicago deep dish style in town and people pay more for your product to get something they can't find elsewhere and even if they can find it then it's not the same quality. 

Do I need a coupon or club card?

For Lowe's, I buy a  "$15 off $50 purchase" coupon from ebay for less than $1  (learn this trick right here in BB forum).

If you google Lowes coupons, you can find 10% off coupons, order the fans through ebates and get about 2% cash back and have the fans shipped to your local Lowes store and pick them up after work =]  

@Alissa Sabbe Not sure about online sources but you can get coupons on ebay for Lowes or Home Depot...they can save you a lot.

@Julia BlytheI've purchased from there before and the unit is warrantied by the manufacturerIf a warrantied part goes bad, I can have my HVAC guy take it to a supply house that sells goodman products and get a new part I've found that acwholesalers is oftentimes cheaper than the supply houses or that they will match the price of acwholesalers acwholesalers also sometimes has coupon codes you can enter to get 5-10% off