You get in with Stage at 99, Standard at 249 or Pro at 399. No need to sweat about it, as upgrading between them costs the same as buying outright.
Stage is like a player version, while Standard allows you to tweak the sounds a lot, and Pro lets you do this at individual note level.
Most importantly, please note that when selecting one of these versions, you then have to choose a "bundle" when you step in: either the acoustic bundle of two fine grands, the electric bundle including Rhodes and Wurli as well as all sorts of Hohner pianos, or the vibes/xylophone bundle.
I went for the Electric/Hohner bundle. 
Next you can (but don't have to) add other pianos. I decided to go with the Model B Steinway, because it's the latest and sweetest. Another good addition is the Blüthner.
Also note that you always get a lot of freebies, including classic grands as well as a great CP80 electric.
So, my advice for a Rhodes lover? Get Stage (or Standard) with the Electric/Hohner bundle, costing you a total of 99 (or 249). Then add whatever you like. You don't have to add anything at any time. All prices remain the same, whether you get them now or upgrade/add later.
And you can always demo everything you don't have (yet) for 20 minutes.

Of course on that organ, it was meticulously sampled by an organ professional and scripted by a very talent gentleman I meant on a forum. I'm not sure what I actually did on it. I love community creation.
 
I've often wondered does anyone actually get the vibes/xylo bundle? I got the acoustic and the electric makes sense, but vibes...  Anyway it is great. I love playing with all the freebies. Just have the stage which was on sale, but even that one seems quite enjoyable and you can tweak it some.

Those vibes should be the works, according to a SOS review I read on Pianoteq...

At the moment I have to say that Heavyocity "Gravity" is a favorite. Haven't done a single project without after getting it.

In addition to the Bluthner and Electric Pianos, I have the Vibes, and it's good. Although I use Orange Tree's Vibes more these days, as their products always seem to have a certain authenticity to them (being sample based). I will admit that Pianoteq's physical modeling is an appealing concept, and it's execution is great, too--they sound great. I am probably going to get the new Steinway B, I just demo'd it yesterday and I really love it (I used to sell Steinway Pianos). Although OTS's Yamaha C7  is a true winner, as well and I use it constantly, too. The pedal noise samples are almost annoyingly realistic.

Please tell us what you think of that Model B, especially in comparison with the Blüthner.

This is a tough one.
 
Ark 1 is probably one of them
Embertones stuff
Oracle
OTS Guitars are amazingly well done
 
So many great ones to choose from. :(

I'm quite certain that most of the best ones are out of my budget due to high cost or prohibitive exchange rates, so my opinion is not based on a great exposure to higher end Kontakt instruments.  That said, I'm a big fan of Resonance: Emotional Mallets by Impact Soundworks.

Will do,Fleer. I can say that I gravitate more to the D4 piano model than the Bluthner, but I like both, and know others that swear by the Bluthner. I tweaked the D4 a little bit, between the tone and the velocity curve, and it's pretty good all-purpose, but lately it's been OTS' Evolution Rosewood Grand, a Yamaha C7 emulation, which would appall my former colleagues when I sold Steinway Pianos back in the day (we bashed the Yamaha's all day and twice on Sundays as being Mass-produced crap). But that Pianoteq Steinway B sounded a whole lot like the actual B's I used to get to play when doing demo's in the showroom, and during my visit to the Steinway Factory (which is an absolute joy), where I got to play there large concert pianos in the special room reserved for the highest of high-roller piano customers/connoisseurs. I kind of miss those days, but never could afford a Steinway of my own. Hence, my growing collection of virtual pianos.  But I digress....

Wow, great experiences! Now I'm really interested in your opinion on the Pianoteq Model B. As for Yamaha C7, OrangeTree Rosewood is sweet indeed, but I tend to go for the ImpactSoundworks Pearl, the Sampletekk TVBO and, last but not least, the ProductionVoices Grand Gold.