Amazon [amazon.com] has 50-Pack 3/4" Gardner Bender Plastic Insulated Staples (White) on sale for $1.04. Shipping is free w/ Prime or on $25+ or $35+ orders (minimum requirement varies by location).
Product Description from Store
UV resistant polyethylene saddles will not rust, rot or deteriorate
Zinc-plated nails resist rust and corrosion
Fast and easy to install - both nails drive together without splitting wood
Nail heads are recessed for minimum exposure
UV-resistant polyethylene saddle will not rust, rot or deteriorate
Fasten 1/2" and 3/4" Romex cables safely and securely with non-conductive plastic staples
Use with UF and NM cable up to 3-conductor (10)
Fast and easy to install, drive both zinc plated nails together without splitting wood
Nail heads are recessed for minimum exposure
Smooth saddle, 3/8-Inch wide, prevents damage to insulation
Fasten 1/2" and 3/4" Romex cables safely and securely with non-conductive plastic staples
Use with UF and NM cable up to 3-conductor (10)
Fast and easy to install, drive both zinc plated nails together without splitting wood
Nail heads are recessed for minimum exposure
Smooth saddle, 3/8-Inch wide, prevents damage to insulation
