Cheap hubs technically have replaceable freehub bodies, but good luck finding one. They're typically as expensive, if not more so, than a new hub of the same model. You can try to find a junk hub in a bin at a coop, but there is no guarantee that the body will fit.
The clicking that you hear is the pawl(s) engaging the ratchets in the freehub body/hub body (depending on the hub). They work just like a ratcheting socket wrench. Volume, or lack thereof, is not necessarily a mark of quality; people generally associate loud with better quality, but Shimano's freehubs hubs are fairly quiet (especially the older ones) and just as dependable for a commuter as, say, a Hope/DT/etc.
If you can find one, and it is worth your time to do, Paul Morningstar made a tool called the Freehub Buddy, which worked with Shimano/Shimano clone freehub bodies. You would remove the freehub body periodically (say, after winter?) and hook up the tool to the space that would be occupied by the bearings, and inject lubricant of your choice into the body, until it squeezed out the other end. It really did work well, but the general inexpensiveness of freehub bodies, as well as better sealing, relative to when he came up with the tool has made it something akin to a zerk fitting on a modern hub: completely unnecessary.