New Rider Looking For New Bike....

Honda CRF 450 X (or F if you buy used) looks like the way to go for you.

It will come street legal (almost).

Since you live in California, make sure that you understand the "Green Sticker" issue:
http://www.dmv.ca.gov/vr/ohvredgreen.htm

Many of the desert areas you can get away with riding without the required sticker, but you are taking a risk. If you ever intend on riding any of the forest areas the proper sticker becomes mandatory because you usually have to pass through a ranger kiosk and they will check. You will also need a US Forest Service approved spark arrestor.

For the sand dunes: I am not sure of Glamis or Dumont but I believe that Pismo is fairly well enforced so I would highly recommend having the proper sticker there.

Have you actually riden a bike in the sand? I hate the sand on a bike. It is a blast on a quad but it is a lot of work on a bike. If I intended to go mainly to the sand dunes, I would buy a quad.

That said, the sand is the one place where bigger is better. In the desert and trails just about any size engine on a dirt bike will have you outrunning a quad. When you get to the sand dunes, those 600 Raptors will definately have the advantage.

I would recommend a 450 four stroke. At the sand dunes, half the fun starts when the sun goes down, so you will want a bike with a headlight and tail light.

So, I recommend a Yamaha WR-450F.

Your price range will almost get you a new bike. If you buy used, I recommend that you buy one with a green sticker and proper title. I believe 2005 and newer will be green sticker, but the older WR-450Fs were red sticker bikes.

Rod