There are several Surface Pro models available for purchase. The cheapest is $799, but that comes with a low-power processor and doesn't include a Surface Pen $99 or the keyboard ($129 for the entry-level standard black option.) That means you should really expect to pay $1,028 for the entry-level model. I wouldn't buy that, though.
Intel's entry-level Core m3 processor is fine if you're planning to surf the web, but the Surface Pro is meant to do so much more.
If you want to take advantage of the pen for interacting with Photoshop, for example, or are running multiple browser tabs and apps at once, I recommend buying at least the Intel Core i5 model with 8GB of RAM. It'll be powerful enough for most anything you throw at it, besides graphics-intensive games and video editing, while also offering great performance. It's the model I'd buy if I was shopping for a Surface Pro. That model starts at $1,299 and, again, doesn't include the keyboard or pen. Tack those on and you're looking at spending $1,527.
This isn't to say Microsoft's Surface Pro isn't a great machine. I think it will be and I'm especially fond of the last-generation Surface Pro 4. If you're willing to live with a last-generation processor, you can get more bang for your buck by purchasing last year's model. The Surface Pro 4 with 8GB of RAM and a Core i5 processor costs $999 and ships with a pen. Add the keyboard and you're looking at $1,160.
Not too bad, all things considered.