2c here to those comparing VRS to Milviz and other devs and complaining about the upgrade price (P.S. I don't work for VRS but having spent 7 years in this industry working for Milviz I do have the perspective of just what sort of sacrifices are often made to make these products).
1: The "maintenance" charge is a legit fee to cover server costs. VRS largely bypasses this though by releasing installers in their support forums when they do upgrades. Milviz can largely get away with lower profit margins due to not charging clients for this service because of the shear number of prodcuts we have available. We have 29. VRS has 1 aircraft, 1 utility (add 1 to each of the preceding if you count the separate P3D/FSX versions), and 3 scenery packages. That's only 5 products. These things don't sell like hotcakes. For a military addon, 1000 sales is a blockbuster release.
2: With the previous in mind, Jon Blum has hired new developers for upcoming products who have to be paid as well. But otherwise the core VRS team consists of 2 people. Jon Blum and Chris Tracy. Chris has a fulltime job to take care of and is the key guy behind the difficult programming that makes VRS products so good. And believe me, creating an aircraft to the level VRS has achieved is not your run-of-the-mill task that some of the other mil aircraft devs have. It is replicating almost single-handedly a feat of engineering that took a whole team of engineers years to complete. Yes it is a lot easier since it is virtual, not real, and we have the luxury of working backwards from the finished product, but the amount of things to design and keep track of is far greater than most of you can appreciate. Jon is full time VRS with a family to support. By comparison, Milviz is over 20 people, many of them part time or able to get income from other lines, with a few full timers and of course Colin has more than one source of income.
If you still think it is less than fair of VRS to expect an upgrade fee (P.S. I have observed a very active and helpful support in their forums contrary to the experience described by some here, which also takes of Jon and Chris's time), that's your choice. I will leave this post here however, to give you all an objective insight into the behind-the-scenes life of developers which I believe many of you take for granted.