Depends what you want to do “routers” basically come in 3 flavours , 1) engraving type machines that have weak motors and small areas , 2) Hybrid engraving machines with bigger beds and <1hp motors and then the BIG buggers , with 3+hp motors etc.
The really big heavy duty stuff is real expensive , but the hybrid stuff is actually better for flexibility. they engrave reasonable and cut reasonably.
We use ISEL 1m x 500mm xyz tables with kress 900w high speed router motors for these. you can cut almost anything on them , but obviously you cant do so at the same speed or depth as the big routers. Our Tekcel will cut 5mm brass or ally in a single pass , our Isel will take multiple passes (5-7) to do the same thing.
I can’t give you advice on which model to get , perhaps your local engraving supply house or a dealer has used models etc?
I don’t think a router is neccesarily the best option in terms of start up for signage unless you have a lot of engraving and routing applications lined up.
I would imagine a print and cut machine is a better bet – or failing that , a laser engraver/cutter.(which wont work with metals)
A laser tends to be pricey but can make you a lot of money.