Vouchers are free to make, there is no service fee for it.
You're just trying to scam people by claiming extra fees.
scamming = is something else
I sell a service , I have a price , I dont force anybody to buy it if they dont agree with the price.
Once a client agree to buy it , I deliver the voucher - so no scam !
PS :
Is free to generate CEX.IO vouchers. there are fees to exchange from your currency in BTC. (take a look at all exchangers and you will see )
I have edited the price : I charge the price of 1 Ghs in BTC (based on CEX.IO & Coinbase exchange rate) + 20%