What makes some Dresden Figurines valuable?
There are a few reasons for the difference in prices. Originally, there was more than one company using the "Dresden" name to produce porcelain.
Differences in prices can be attributed to the age of the pieces, the size, the quality of detail, and specific studios that were operating under the Dresden name.
If I were purchasing a piece of Antique Dresden I would be looking for a much more simplistic mark with a light blue hue.
With that being said, your piece has a few things going for it. Although it is hard to accurately gauge the size of a lot of the items sold on sites like ebay it's easy to tell when they are not miniature and if it has 3 figures in it then you canguess how big the scene is going to be. Usually 5" at the base.
Take a look at the quality of details in two specific areas: the faces and the fingers. The fingers on your statue appear to have very poor detail and are quite "blobby" and undefined. Look at the left hand of the lady seated playing the cello. Look at how large the finger next to her pinky appears to be compared to the rest of them. (Side note, I think her middle finger is chipped, examine all of the figures hands closely for chips). If you look at their eyes and the lack of real detail (solid 1 color in their clothes) and compare it to some of the top examples of that sold on eBay, you can see what I am talking about.
I'm not an expert on Dresden or anything, but I deal mainly in antiques. You would really have to ask someone who collects these. When someone collects a thing, they have very specific reasons for it. I think as resellers it's hard for some of us to understand that mindset.
I hope this helps!