Cheapest Packing Tape — Bulk Rolls & Dispensers
Packing tape is the one supply every shipment needs. Acrylic tape is the cheapest and works for most packages. Hot melt tape grips better on recycled cardboard and in cold warehouses. Water-activated kraft tape is the strongest option — it bonds to the box fibers themselves, which is why it's required by many freight carriers for heavy shipments.
Current listings — sorted by price

Acrylic Packaging Tape, Clear, 2 in x 110 yd, 2 mil, 1 Roll

Tan Acrylic Packing Tape Carton Sealing 1.88 Inch x 110 Yards 1.75 Mil 36 Rolls

Clear Packing Tape Heavy Duty 2 Inch 65 Yards 2.7mil Hot Melt Adhesive 12 Rolls

Water Activated Gummed Kraft Paper Tape Packaging Dispenser 3 Inch for Shipping

2" Tape Dispenser Tape Gun Grip Heavy Duty Packaging by HAL

72 Rolls Carton Sealing Clear Packing Tape Box Shipping - 2 mil 2" x 110 Yards
Buying tips
Acrylic tape ($0.80-1.50/roll) is fine for 90% of shipments. Only upgrade to hot melt ($1.50-3.00/roll) if you ship in cold environments or use recycled cardboard.
Buy in cases of 36 rolls — per-roll cost drops 40-60% vs. buying 6-packs from office supply stores.
A 2" wide tape is standard. Only use 3" tape for heavy-duty or oversized boxes where you need more coverage per strip.
A pistol-grip tape dispenser ($8-15) pays for itself in the first 50 boxes. Hand-tearing tape wastes material and looks unprofessional.