You can use Vault to enable economy with SimpleClaimSystem, don't forget to enable the "economy" setting in config.yml :
# Enable/Disable the economy system (sell/buy claims)
economy: true
max-sell-price: 1000000000
# If /claim is paid
claim-cost: false
# If claim cost is multiplied (for example if claim-cost-multipler = 2, first claim will be the claim-cost, 1000 for example,
# the second claim will cost 2000, the third one 4000 ..)
claim-cost-multiplier: false
You can setup the max sell price, the cost of claiming, and the cost multiplier.