My first router table was pretty crudely banged together out of a countertop cutout and some MDF off the scrap pile. The problem was that the tabletop sagged, so on long boards I got a serious variation in depth of cut. I needed more precision for htre current project, so I built router table 2.0 this weekend.
I still am using cheap material. The melamine for the top came from the cull bin at Home Depot, as did the MDF sides. The craftsman fence was bought from a woodworking forum member, he got it on clearance, so I got it very inexpensively. It's nice aluminum extrusions with T-slots all over them for mounting featherboards and other holddown gizmos. It also has a dust collection port on the back, and you can flip the left extrusion around and do edge jointing with it if you don't have a jointer. I need to work out how to clamp it to the table top, but that's not a big deal.
Anyhow, here's 1.0:

And 2.0:


The table top on 2.0 is made to be replaceable. The walnut buttons hold it into a goove on the inside edge, and I can make a new top in a few minutes. I did cut some hardwood edge banding for the top, but it's not applied just yet. The top is well-supported this time to avoid the sag issue. My fixed base Milwaukee router is just screwed to the bottom of the tabletop.
I've got about 5 bucks materials in the table, and 40 bucks in the fence. If I didn't get that fence so cheap, I would have made one in MDF, but I like the aluminum.