Hoochie , adjustable Glock sights are a factory option , IIRC they charge about $ 35.00 for them installed .
The guy who said " if you have to ask - you can't afford it " wasn't taking about Glocks , They are a very affordable option .
Also , IMO , you don't have to justify a negative situation this guy had . It doesn't matter , The sales guy's job is to educate the buyer and make a sale that leads to a happy consumer . Or refer him to someone who can . A crappy retail experience is just poor service , doesn't matter who or how the customer is .