What if someone is giving away a gift to some as a time-limed, promotional incentive, and charging for it later? The case that caused me to wonder about this practice is a local synagogue offering free rain ponchos to encourage attendance at Friday night services tonight (the weather forecast calls for rain), and charging $10 apiece (as a fundraiser, I assume) otherwise.
Is this a problem of usury? Is it a different problem? Is it no problem? Is this any different from a candy store/bakery owner giving kids (or others) free samples? (Ie., would one be allowed and the other forbidden? If so, which, and why?)