cash/roses
credit cards -  if they can accept this payment type, the provider will have a side business or company name.
Pay-Pal - same as the above w/ credit cards
Post dated checks
IOU's
and believe it or not, a Best Buy gift card

Not too many providers will take a credit card but some do.  As an example, Karen Cummings in Vegas took my visa years ago

Is it safe? Does your wife investigate every charge?  If not, its safe. Its about the same as ordering a box of Omaha steaks online with your mastercard.  The transaction is secure, but you might want to find out what the name of the charge will be on your card.  

Hope this helps.