Just a note on why M sleeperi is not that available. The beetles are not super rare but not that easy to find. The locations are very remote and your timing has to be almost perfect. There are years I have gone out 4 or 5 times in spots I have collected them before and got nothing. Just depends on the year and weather that year, etc. I know many collectors that have struck out many times and that gets frustrating. It's a long drive to get nothing. When you do get them, it's really rare that you get more than 2 or 3. So it's not like you are going to hit it perfect and get 10. This is my experience and have talked to many other collectors and it's similar. However, there could be someone out there who has a great spot and gets them easily, I don't know.
M punctulatum is much, much easier to get. If I went this year to try to get them, I would say I had a 90% chance of getting them. The only issue with Mp is that the females are much more difficult to get in numbers than the females. You could easily find 50 plus males on a decent night and get one female. However, in all my years of going out for Mp, it's very rare I come up empty. Also, the locations for Mp are not remote like M sleeperi. Many spots 10 minutes from a town. The only spots I know of for M sleeperi are many miles from a city and not easy to get to.
Anyway, I think some of these reasons is why they are not that available. They are not rare but just not that easy.
I have no experience at all with M vogti but the collectors that I know who have collected them tell me that the locations can be difficult because they are often on private land and you would need permission from someone to collect there. You need to go after a summer rain, so timing is key as well. So for those outside area, you can't really plan a trip in advance.