For 2D you need an affordable base, really don't even need the rover unless you want to localize your elevations of the job site. Been down this road lots of times if you have any questions. If you come up with a base all you have to do set the base up and go bench on a known elevation and work from that. You can find used bases fairly reasonable, the expensive stuff is already on the dozer.
I'm late to this party but I see an opportunity to learn something new.
Is it possible to set up a Trimble base station on a new site without connecting it to a data collector? Every time I move our base station to another site it gives an error message (I forget the exact wording) until I connect a data collector and set it up on the new site.
It's easy enough to set up a flat pad, sloping pad, slope, swale, etc right from the screen of the CB460. If you have the rover you can design a more complex site including flat and sloping pads, swales and driveways right from the site itself using the data collector. You can then export your design to the CB460 in the dozer using a thumb drive. Get a good used base and rover setup. You won't regret it!