Does a river cruise have to be expensive?

Does a river cruise always have to be expensive? I don't think so, for several reasons.
Before I answer it though a bit of background information on river cruising may help, (you can click here for a previous post I've done on the pros and cons of river cruising).
River cruises are the smaller cousins of their ocean going counterparts. For obvious reasons they are built on a much smaller scale so you get a much more intimate atmosphere onboard and they just sail up and down the different rivers of Europe, Russia or China, dropping their passengers right into the middle of a town so they don't have the long transfers from port to town like so many ocean cruise have to do, (Civitavechhia to Rome anyone?)
This means that the focus of a river cruise really is on the itinerary and not the ship itself.