S-Pen from Samsung galaxy note devices work as well if not better than the surface pen, does not erase though, I don't think. Also for a more pen like experience you need the stylus holder from Samsung as well.
Wacom recently started selling the Bamboo Stylus Feel for devices using the Wacom Feel IT technology. Two versions starting at $39.99 . These are a capped stylus with 1024 levels of pressure sensitivity.
As far as the tip moving up and down that is the pressure sensor, and all these types of stylus are going to do that.
They appear to be, and since the Surface Pro, as well as the Galaxy Note 10.1 incorporate the Wacom Feel IT technology, they would seem to be an ideal alternative. Of course, I really detest the term sharing, like we are in some kind of AA (Android Anonymous) meeting here
Anyone know if there's an eraser function on the back of the bamboo feel? There is no description of the functionality on the Wacom site. I like that it can use a hard or soft tip; though I wonder if you can just get spare tips for that thing and put them in the stock MS pen (which I don't mind at all).
The Bamboo Feel does not have eraser functionality unfortunately. I would have though the original MS Stylus would have come with both types of tips, my Galaxy Note 10.1 did and I much prefer the softer tip. Samsung released a stylus, but I think in Korea only, that has an eraser. Even though the offers I've read say it is made for the Feel IT technology I'm a little leary.