You pay for what you get, most of the time.
What would you pay, to gain the skill & KNOWLEDGE, to be an 8 speed player or better.
Don't forget knowledge, there are many bangers that can shoot balls in from anywhere, but have no concept of cue ball control.
A good instructor will give you a great foundation, for you to begin building upon. Bad technique or bad habits can limit your possibilities of becoming a good player. A good instructor can dial you in & assist you in developing a good technique, while in transition from bad to good or from novice to intermediate or from intermediate to upper level player.
What does that cost....? Depends how bad you want to be a 9 Speed Player. Instruction is just one part of learning to play better, practice isn't free either. Coaching along the way adds to the cost. Videos & books add to the price. Once knowledge is gained, application skills need to be refined.
Would you pay $3000 to be a 9 Speed...? I'd borrow twice that money by lunch today, for the assistance to that level. 2 weeks of $100 9 ball, will get your money back.
Good Luck....