IFMGA Mountain Guide and Outdoor Research athlete Chris Simmons hears all the time about the value of his services. He also hears about how it's cheaper to just have a friend teach you to climb or ski. He recently sat down with a pen and a napkin to find a way to explain the benefits of professional instruction.
If you want to have the most effective (time+effort) experience or instruction, consider hiring an IFMGA Mountain Guide or a PSIA 3 Instructor (for ski areas). Everything else is just a compromise. If someone chooses to save money in equipment and professional instruction in the spirit of "DIY," they should be prepared for developing at a slower rate, and learning more lessons by mistakes. At some point on the graph, usually depending on what your final desired outcome is, trying to save that money in the beginning actually costs more in time spent correcting those mistakes.
Sometimes it pays to be cheap. But at some point, you pay by being cheap.