Just to add a little info. In my experience Dan is very difficult to get a hold of by phone. I have only talked to him once and the call back came a week after my message that I left him. I have found that he is much more responsive to e-mail. That has been my main form of communication with him and the responses have been typically within 24 hours. His business is a one man show.
As far as costs, I paid $2300 for the RPM Box with the modified CV cups and no brake. As Pilot said you will need Gorilla axles ($800) as the plunge on both ends. The Calipers for the outboard brakes that are typically used are the Wilwood PS-1. There are 2 versions, I used the ones with the larger pistion, 1.120"and they run about $90 per caliper. Then you need rotors, RZR 800 rotors will work, get a set on ebay for $50. You will need hubs, the fireball racing RZR 800 hubs will run $400. You will need to fab brackets to mount the calipers. I bought CORE brake lines as I could have them custom made to the lengths that I needed. They are -3 lines and ran around $150 for both lines and came with banjo bolts.
You will need to be prepared to fab mounts for the gearbox. I have an extra set, I had 3 laser cut when I did the conversion or I can share my cad files and you could have them cut yourself and weld up. I think they cost about $110 per kit when I had mine cut.
You will need the pillow block bearing ($120) and to fab a mount for that too. Figure about $75 - $100 in materials for the mount.
A torque bumper bracket will need to be fabricated to maintain belt tension between the motor and the gearbox.
So, doing the work yourself you can expect to invest over $4000 to do the conversion.
Here are two links where you can see some of the work involved.