Gaffers tape is not an item commonly found in hardware stores. Since it looks so similar to duct tape and costs twice as much, it is a tough sell for most retail merchants.
If you live in a city large enough to support a theatrical supply store, you can probably find it there. Even better, stores that stock supplies for film and video producers will always have it.
Forget about big box stores like Home Depot and Lowes. They sell tapes that have high demand and they count on quick inventory turnover. Gaffers tape does not fit well into that environment.
Most users turn to online sources for this type of tape product.
GoodBuyGuys is within two days by regular UPS Ground shipping, so we can get whatever you might need into your hands within a couple of days.
If you are in a hurry or you need something right away, check this shipping time map before you get in the car and begin your search.