I dont think they are being ripped off, though prices certainly are high.
Two factors at play really - golf is a rich mans game in general, and, the nature of the game does lure him into always looking for some tool or angle that will improve his performance.
But golfers choose the high price gear. Its as if car buyers were only willing to buy a Ferrari, a Roll Royce, or a Porsche, and regarded anything else as not to be taken seriously as worth buying.
There is no such thing as a 'golf shirt'. Its just a polo shirt that you can get in any dept store for less than a tenner, or £20 for a 'premium' one. So anyone paying £70 for a golf brand shirt as worn by the tour players is choosing to do so, even though of course the manufacturing price of both is similar. We can buy the Benross, or Slazenger gear for 20 or 30% of the major golf brands.
You can get a decent pair of golf shoes for £50. But people will pay £200 for a pair of golf shoes that they will only wear for 4 hours 20 or 30 times a year, when they are probably wearing a £50 pair of Clarks street shoes day in day out. Then he starts obsessing and posting on forums for reviews of what studs he should have on tham, and spends another £20 because the ones on the shoes from the box dont quite suit the soil at his club apparantly. And he needs different ones when he plays when on holiday in Portugal. Oh, and the pair of 'golf' socks for £15 while he is at it.
Putters for £250? Is madness. But you dont have to buy it. The no name brand beside it for £30 is to all real analysis the same thing.
Irons havent improved in any meaningful way in 30 years. Drivers in 15 years. The genius of the club manufacturers is adding stripes and colours, and gimmicks like movable weights or adjustable shaft angles to create the illusion of improvement when none exists from year to year. Yet people delude themselves, handing over £400, that since thieir driver is now 3 years old that they are up grading.
So people arent being ripped off - they are choosing to spend such money because the have it. And the golfbrands of course are going to take it - its almost that the more expensive golf gear is, as long as a tour player is using it, the more the golfer dreams it will help him and will hand over his money as part of that dream.