Wow I always assumed the replicators were based on a conversion of energy to mater, like a transporter pattern (though I gather this would take immense energy). This explains the economics a little more. It makes sense that people would still trade things, especially things not easily replicated. So uranium is still potentially as rare as it is today, and still a commodity. Its hard to replicate it, unless you have uranium (in which case uranium is pretty much juts beamed to the replicator).
Iiiinteresting