Let me add Crimson Trace to the list. I bought laser grips for a Walther PPK/S several years ago. They have since redesigned that model do to variations in a gun made since 1931 under various licenses... The first set didn't fit my gun and the piece between the grips tore. No problem, I called, and they said send it back with a note. Shortly the engineer working that product called me for feed-back. And shortly I received brand new grips that fit with a bit of minor file work to shorten a small tab.
They have redesigned using a cam system to fit the different size frames. I sent my old, laser on the left where it blocked the mag release, and a check for $179. A week later I received the new, very nice, redesign with the laser on the right. The grips slipped right on, I didn't even have to change the cam defaults for my gun.
Both quality product and great service. Not cheap, but well worth it for those of us who don't see well in low light (or good light for that matter, any more).