First of all, you have to make them familiar with SFI and TripleClicks. Let them know that currently, TripleClicks has around 1.900.000 members, in 203 countries worldwide, and it also has more than 5100 ECAs with more than 100.000 products at the moment.
Tell them that it cost nothing to try it. They can only benefit from it.
One of the rules in SFI is to Lead by example. So my opinion is, if you can, open your own ECA and show them how are you operating your online shop. Regards