Choice method for purchasing credits at online casinos used to be a method called firepay, where players would seek out “firepay casinos”. Where players could use a online webwallet provided by FirePay to purchase casino credits.
There was several problems with firepay as some players accounts were hacked other issues where the online casinos could not provide the best service using firepay webwallet. When Neteller dropped service to US and Canada, Firepay pretty much dropped out of business. You wont find any FirePay casinos but there is many other webwallets to fund your casino accounts with.