You can send through FSN. Call your rep and they will explain how to do it. You can do it on the web ($3.99) or over the phone ($6.99). They choose the florist or you do (within the network). You put a credit/debit card on file with them and they charge it when you send. If you send a $100 order, they bill your card $80. You can charge the customer for the service. For example, you can charge your customer a $7 service charge and phone the order to FSN. The $7 covers the cost to phone the order. They bill your card 80% and leave 20% in your bank.
Since you already use FSN, I would recommend at least trying it. Tell them you want your first 6 orders free.