My goddaughter has a VISA BUXX card, mostly because I nagged her mother into it. It's wonderful. You can control the maximum transaction, where it can be used, how often it can be used, whether mail order and WWW is OK or not, what can be bought--all sorts of things.
The only difficulty is that doting godmothers can't just add cash to the balance. Only parents can do that.
My goddaughter is a super-sharp shopper now. She comparison shops very carefully and ponders all the options. She buys a lot of her clothes and accessories (she's 16) by mail order and on WWW.
Her mom puts her allowance on the card, too. The student store at her high school takes VISA, so she can buy all her school supplies, including uniforms, too. Her mom says it's a real help, because she doesn't have to send cash or go herself.
Go for it!
Mary