I am happy to report that I just received a new replacement stylus for my n810, but it was more of a pain (and more expensive) than I would have liked. Here are the details:

• I posted previously on this thread that I found them available at handyersatzteilshop.de. Their web site didn't let me ship to the US, so I ordered by phone. I stayed up until midnight in California, which is 9AM there, and ordered from Andreas. I ordered on April 3.
• The cost was 8.32 Euros plus 5.99 for shipping. This is about $23 total. I don't know why the cost wasn't 9.90 as listed on the page. Maybe because I didn't have to pay GST.
• They weren't very communicative. I never got an order confirmation email, and my email 9 days after the order asking if it had been processed/shipped was ignored. But I called them again later and they confirmed that it had shipped.
• I received the order today (4/19), so it took 16 days total.
• I can't read German, but the picture on the item description page shows 3 stylii. In fact, I only received one. A Google translation says "Content: 1 piece", so I guess that is the right number. Still, I wish they would change the misleading photo.
• The stylus is original (Nokia branded) and works perfectly in my device.

So while things weren't perfect, I'm at least happy to have a working stylus now. And I'm going to be very careful not to lose this one! I contacted many US stylus retailers asking them to stock N810 stylii, but none agreed to do so. A couple mentioned that dealing with Nokia is a pain, especially if you are not a phone retailer. I do love the n810, so I hope the stylus availability picture improves. Nokia needs to make these more available in the US, and they should try to at least standardize on one stylus form factor for their future internet tablets. I wish they would use the same form factor as the Palm Pilot, as I can pick those up cheaply at numerous stores in my area.