A P2000 will cost $150 to $200 more than a P99. I can't tell you why they cost more...but I think you're paying for the name. That said, its a great firearm. I have not shot one, but I came close to getting one over the P99. It felt good in my hand. As a left handed shooter the fully ambidextrous controls were very attractive, but they weren't worth the extra $150.
When are the new P99s supposed to be coming out? A good place to get a bottom end price is at Gunbroker. Be sure to add shipping and FFL transfer fee (if applicaple) to the final price. Check at gunshows too. When I bought my P99 this past November the best price I saw was $520, highest was $615. I bought it at my local gunshop/range for convenience and customer loyalty for $595.
I guess you've already got a P99, so a P2000 might be a better option. If I was a person without either, I'd go for the P99 because of the better price (and better looks!).