It's rare that I have a buyer buy more than one thing, but if they do, they usually buy at least 1 paid postage item. If they buy more than one paid postage, they get the reduction and the 'free postage' items thrown in. I have heard of others throwing in a freebie to the value of what the postage would be to make up for it.

I buy plenty of stuff with 'free postage' and I never really think about how much extra I would be paying compated to paid postage. I doubt I'd be the only one.