So looks like the pricing is highly variable. There are 5 editions of CS3, and each edition has a "lite" and "full" samples variant. The cheapest is $200. Each edition up adds $50, and going to full samples adds $100 giving $500 as the top price.
There are also two specials happening related to it. Anyone can preorder the full samples edition 5 and get a 15% discount, this lasts until it launches but the discount is only for the full edition 5, nothing else can be ordered. So $424. If you are an existing customer, you can then take 10% more off, for a total of $381.
However, Kirk Hunter also offers tiered discounts for customers, based on how much you've spend total in the past. Those start at 10% and go up to 50%. If that discount is more than the 25% off, you get it instead. So like in my case, I get 45% off. That discount, being a general customer discount, should apply even to the other versions once they are released.
So basically getting CS3 could cost you as little as $100 or as much as $500, depending on the options you want, and the discount you have :D. A bit overly confusing, but I guess he wanted to offer flexibility.
In terms of differences lite samples are 10GB, full samples are 75GB total. I'm not sure what lite cuts out, that isn't specified. Probably some round robins, halftones, maybe some dynamic levels.
The editions are just how many features you get. The Edition 5 gets you everything. Edition 4 drops the sordini and portamento playing styles, and the ability to do custom runs and fills. Edition 3 also further drops trills, and separate control of ensemble chairs. Edition 2 further drops volume and pan controls for ensemble chairs, and control over tightness of section. Edition 1 further drops connected bowing, hand position shift, tremolo, intervals between overlapped notes, and microphone distance control.