I've been twice. The first time I had to get my watch (Tag) band repaired. The guy mentioned there is a special piece required and charged me about $80. I thought this was high, but he gave me a thorough explanation (including drawing out a diagram), so I took his word for it.
My watch battery died later, so I went back. He at first mentioned that I could either pay $30 or $40! Now I've changed batteries before, and pay around $10. I told him as much, and again he gave me a long winded explanation about why you shouldn't use generic batteries for a Swiss watch. I did mention that I'm not going to pay that much, so he brought down the price to $20 (since I was repeat customer)
Now I'm wondering how much I overpaid for the first visit!!
He does seem like a nice guy though, and I do think that he genuinely wants to do a good job... but he may be "overprescribing".
Also, even though the place accepts card, both times I've visited he's asked me to pay cash when I tried to use my card.