[Potato Uno]

...how much would the SM devs be charging (per hour or flat) for their time, expertise, blood and sweat spent on development?

Looking at Sourcemod and Metamod in closer detail, the amount of knowledge and effort put into it is mindboggling (and that's not counting the reverse engineering needed to make it all work), and the fact that it's available all for free (<3 GPL) is even more crazy.

So, suggest or speculate what an appropriate rate would be if this was done as a full-time paid job.