You can't get a disk per se from GOG, but once you buy a game there, you get access to an installer that has no DRM in it. You can then download it as many times as you want, or you can store it somewhere, burn it on a disk or do anything else you like with it. I have MM7 and MM8 from them, and they work great. Moreover, their games are often better tuned to work with the modern systems, so there is less chance that the game will refuse to run until you switch on some obscure compatibility settings etc.(Currently, the MM's seem to be at roughly $5 a game there. However, occasionally they are on sale, and then they're dirt cheap — when I wanted to buy them there a couple of years ago, I was lucky and they were on sale. I paid something like 2 € total for MM7 and MM8, which is next to nothing, especially compared to how many hours of great gameplay I got from them.)
