three $1 Postage Due stamps on that package. You would at least get something of philatelic value for your three bucks, as some stamp collectors took a fancy to high-value postage dues. I guess actual postage due stamps have gone the way of the Dodo.

Comment about putting on the $3.50 with your own stamps and mailing: the price includes tracking but you need to have a tracking label to fill out (and keep). Otherwise you pay for a service that is not being used, the post office cannot scan the bar code and actually provide tracking for you.