I was able to preorder the D7100 over the phone after all, from Bel-Air Camera. The last time I tried, the rep I spoke to said I would have to physically come to the store. This time I spoke to Rika and when he found my customer record, he took the preorder by phone. I'm not sure if that's something they do for everyone or just existing customers.
BTW Rika said the D7100 might arrive before 3/21/13. In any case they'll call me when they get it.
You may be wondering why I ordered from my local store instead of through Amazon or some online retailer. First of all, Bel-Air Camera is a good store and I want to support them and other local businesses when I can. Second, because the D7100 is so new, it could develop issues and if that happens I want to be able to talk to a live person face-to-face and resolve the problem then and there, not get bounced around through some voicemail system. For example, when my D600 got spots they took a look at it and cleaned it for me. Third , I know I will get my camera at least a day ahead of online orders that have to be mailed. :)
What about sales tax? AFAIK, most places that have a sales tax also have a use tax (California definitely does). The use tax is the same amount as the sales tax and is triggered when you buy something from some other state and don't pay a sales tax. So you ought to be paying the same amount either way.
If you're interested in the D7100, please join the Flickr group for it right here. I will be posting there regularly.
On a separate note, I ordered an autographed copy of Neil van Niekerk's book the Direction and Quality of Light. I got the book because I am passionate about lighting and because Neil thinks that this is his most essential book about lighting, and I owe practically all my on-camera lighting knowledge (and more) to him. So I am taking Neil's word that it's worth it. As for ordering the book, I ordered it directly from Neil because it's my way of saying thank you for everything that I learned from him. Yes, it's definitely more expensive than buying from Amazon or some other source. But what I learned from him was definitely worth waaaaay more than the $12 or so extra cost. Anyway I will be reviewing this book when I get it.