If you use anjuke, you can see the last 3 years worth of data. I would guess prices are up about 50% over the last 4 years. Prices in Kunming have been rising much slower than other Chinese capital cities though.
I would hardly call Dali Old Town overdeveloped, unless of course you are talking about the tourism industry. It's quite backwards in most other regards.
The best way I could describe it is you get all of the inconvenience of living in a big city (noise, traffic jams, high cost of living) with few of the ammenities (reliable power and water, access to schools and hospitals, shopping, skilled workers etc).
I was going to post a similar topic last week, but didn't because usually such questions don't get very good answers. This is largely because the information is generally not available to the public. The last I heard was that the rail link would be open by the end of 2019. Do you have a source for the 28th?