This request is a bit complicated. Think of the Skyblock challenge system, you trade in items for perks or levelling rewards. In my SMP server, I thought it would be a cool idea for players being able to purchase permissions with things (for example 32 diamonds for 'essentials.sethome.multiple.<>'). If there is a plugin like this or similar, it would be great if someone could redirect me to it. This thread might be under the wrong forum, and if it is, please move it, thanks.