It really isn't that hard to build a top or you can just buy a top depending on what you want to do. Several issues of Shopsmith and Woodsmith both have complete low cost set ups with complete instructions. I built one years ago if I remember correctly from a Woodsmith article that you c clampled to the end of a bench so it was able to be put out of the way. My costs in it were $50 I believe and I used it for years. On another note, I believe Insomniac has pictures on his web site of his previous router table on saw horses. To me, it appears to be quite sturdy and not hard to build.
Most of the ones at HD and Lowes are not the greatest IMO and the Bench Dog's and others are top dollar to have to spend when you are getting started good.
My recommendation is to check out the on line stores, read the reviews and see what you like and don't like. I would also do an online search of Woodsmith's and Shopnotes article index as they have pictures a lot of times or downloadable plans you can get. I would get the whole mag versus the plans just because I think you get more for your money.
If you do build one, use it for awhile, decide what you like and don't like, and go from there.
IMO, the two most important things for a router table are a flat top and a fence that is square to the top.
