Budget Padding Backpack straps Handle Material Zipper Pocket Budget Generally speaking, a decent entry-level guitar bag always cost about $30-$40. The most important characteristics must include the following details. Padding 10mm (2/5″) padding is the basic requirement. Sponge and EPE foam is the most common materials that can be found in gig bags. Compare with sponge, EPE foam absolutely performs better in impact resistance and durability.