I used a store bought router table first time I ever used a router. Did it's job, but I've made 4 or 5 since, making changes and improving, each time. And figure I have around $2. 50 in it definitely less than $5. That's for the bolts, nuts, and washers that hold it in place. The rest is all left over 1/2" plywood, and 2X4 chunks. The top is 3 pieces of 1/2" plywood, very well supported by a spider web of 2X4 pieces under neath, no sagging on the last one in something over 10 years. Router fastens on a 1/2" plywood router plate. Have multiple plates, so can swap out routers and bits in less than a minute. Quite possibly the most least good looking router table here, but it does exactly what I want it to do. With what I do, have never needed a fence, but if it comes to that, I figure a chunk of 2X4 fastened in place will work for me. Oh yes, except for 3 or 4 bolts, the rest of it is held together with Titebond II.
There's a thread, long thread, very long, of homebuilt router tables here. Check that for ideas before you do anything else. Got some great ideas there, and you can even see mine somewhere in there.
And possibly the best thing about making your own router table is, you are making just what 'you' need, and not buying what someone else thinks you need.
"It ain't what you're told, it's what you know." - Granny Weatherwax
Some days, the supply of available curse words is insufficient to meet my demands.
Call me a craftsman, artisan, or artistic, and I will accept that. Call me an artist and you will likely get a quite rude comment in return. I am not a @#$%ing artist.