The other thing I like about Sam and The Cop Shop is the personal service. I took my 23 to them some months back and had the tritium sights installed, while I waited without calling ahead.
Sammy also took the time to show a few other options to me as far as other accessories.
They do good work if you need repairs and if need be will send the weapon back to Glock for you.
If you catch Sam Sr. at the right time you will also get a great joke or two!