From what I've heard, Robben no longer plays his signature model (like Joe Perry). He plays an old Tele or a 335. I always find that amusing/embarrassing for whatever company makes the guitars.
Just came across this old thread. There are two eras for the Fender Robben Ford model, which is a variation on the previous Esprit. The first Robben (essentially the same spec as the Ultra SP that came later, but with an alder back vs mahogany) was made by Ibanez, production ran from '89 - '93. These are outstanding and usually affordable, though they are starting to appreciate. In '94 production (in smaller volume) was transferred to the Fender Custom Shop, where there were three models, the less ornate (and most common) Elite, and the Ultra SP and FM. The Ultra SP has a spruce top, the FM is flamed maple.
While the Custom Shop guitars are gorgeous and extremely well made, they generally very expensive, if you can find one. I have two of the first generation Japanese models, and have had one of the Custom Shop Elites. IMHO the early ones are the better guitars all things considered.