Reverb Bump is a system that lets you pay an additional amount when an item sells to promote your listing within Reverb.
For used items, Reverb sellers can buy a package of bumps, which are priced according to the price of the item listed.
For items listed in Brand New condition, there is an auction system in place that allows sellers to bid for premium placement. Check out this section of our Help Center for additional information on the "Bump for New" system.
For more information on the ins and outs of what bump can do for you, as well as pricing, check out this page dedicated to Reverb Bump.