Stephanie, look at the economy table top thread in this section. You can clamp the table top to your bench for now with two C clamps.. The fence can be made from a piece of 2x8" with a 2-1/4" hole drilled through it for your vacuum hose. Two 6" C clamps will hold it in any position you need. You can make a simple circle jig to cut a recess in the table top and mount your router to the back side. Later you can add a mounting plate and enlarge the cut out so there is no waste.
4 C clamps from HF should set you back under $10. If you get the phenolic impregnated Baltic birch plywood from Rockler about $20. Not a bad way to get going.
"Living in the D" (this means Detroit!)
"It's fine to disagree with other members as long as you respect their opinions"