For those interested, I've recently added several hundred more prices from eBay to the database at XYZ Collectibles. The link is
Click on the little dollar signs to the right of each issue and it will show you the details, including the condition of the magazine, the seller and the date of the sale.
There are prices listed there up to the present day, but this round of additions only went up to 1920 -- it's quite labour-intensive to add the data and after 1920 the prices aren't high enough to make it worth adding a lot of extra data. There are now over 1,400 sale prices in the database.
A couple of observations based on the data so far. First, it's possible to get really good deals if you're willing to wait. New sellers, and one-time sellers, often put magazines up for auction at low prices. This doesn't apply to the really valuable (pre-1900) issues, but much past that date and there's a chance that a particular issue with a low starting price will sell for not much more than that price, if few bidders for that issue happen to notice it. For example, this:
is a May 1918 issue with supplement in good condition that sold for 99 cents. Two other copies of that issue recently sold for $26.99 and $19.99, without specifying if the supplement was included.
Second, and conversely, if you're selling, you should put your magazines up at a price that is comparable to the prices of the dealers who are selling successfully, and have patience. Put it up at a "Buy it now" price, and wait. Auctions almost always get lower prices.
Finally, and this is more of an impression rather than something based on the data, to get the best price, put up multiple pictures, including both covers and the spine, and provide a description that tells the collector what they are interested in hearing. Many of the lowest prices were from dealers who simply put a magazine up with one, or maybe two, pictures, and little or no description of any possible flaws, the condition of the spine, or the covers. Few buyers will risk buying a magazine listed like that.
If anyone would like to contribute data to XYZ's database, please go ahead; anyone can do so. I'll probably put a bit more data in later this year, but I'd really like to gather data on some of the very early issues that don't go on sale often. If you have records of what you paid for some of the early issues, I would love to get that data.