Pig Zombie/XP - 50k MTC <- overpriced, i better buy myself my own pigmanspawner...
Record Farm - 15k MTC <- have my own one
Skele/Spider/Zombie/Creeper - 100k MTC <-- I use /warp archtrap, i only need 10k creds for perm or soem spawners and i get more that your farm will ever spawn...
Iron Golem - 50k MTC <- lets take a look into the zoo...
Sheep - 70k MTC <- for what you need? a normal spidergrinder is better then 1 sheepspawner!