If you want to change the price for a listing on the vshop, it can be a messy process to /cancel your stock and resell them, especially if you're selling bulk items. Thus, a command such as /relist would prove useful, as it allows you to relist your stock without /cancelling all your items.
For example:
Metr0n0me is selling 5000 dirt for 2 meebles each.
/relist 5000 dirt 1--> changes the price of all 5000 dirt to 1 meeble each, and charges me 5000*.05=250.
/relist 2500 dirt 1--> changes the price of 2500 dirt to 1 meeble each, charging me 125, and leaving 2500 dirt for sale at 2 each.
What do you think?