You could try looking around in the used club bins for an iron similar to your own set and have that lengthened. Try it at the range and see if it helps.
1. Yes I have and it sure does help. Playing with
clubs that don't fit is a form of self abuse.
2. I've never had an extension break. Never gone 3 inches though.
3. I know a Pro who plays
clubs that long. I think he is 6'6 or 6'7 and has no choice.
4. Use the phone to compare quotes. Might want to get a second opinion as well. Don't rush into anything. The golf business is the same as any other business - you have money, they want it.