https://www.spigotmc.org/resources/guishopplus.15561/
But to auction spawners you'll need
https://www.spigotmc.org/resources/auction-house.6050/
Then just use the first plugin I stated, I thought you wanted players to auction spawners.I mean I want players to be able to buy spawners from the server. Not allow players to sell there spawners to other players.