Some strategies are valid but just not scalable, so people "share" them and "scale" them this way.sure....many do. for example: claytrader, warrior trading, and your fellow et member larry williams etc.
Personally, if the strategy can be backtested, it can be automated and thus can be priced. Discretionary? It is just a method which may or may not be adoptable. I would not pay much in advance.
There are people who have strategies which require either large capital or large tech investment or both. So it's "easier" to sell them and invest in something else.The age old question comes up - if a strategy is that good why would anybody sell it?
I have heard from a friend of someone selling his automated strategy for a few millions and the shop that bought it made ten times that before but it stopped working.