Ever had a buyer send you a message, asking for a LARGE discount - simply because they've got "more work for you in the future".
This might sound great, but there's no guarantee they're place multiple orders with you. Even with the subscription offering on Fiverr - they can back out at any time.
I once heard a great tip, so feel free to use this if someone offers this to you:
Respond with: "Sure, I can do discounted pricing for repeated orders. The first order will be my standard rate - but the second and third orders will be 5% and 10% discount respectively, and 10% thereafter".
This way - you're offering a discount for repeat orders, but not risking the client placing one order and ghosting you!