I'm wondering about Glock's factory-installed night sights. They add about $70 to the cost of the G19 I'm looking at. Are they made by Glock? If not, who makes them? Regardless, are they worth the extra up-front cost, or should I get an after-market brand? If after-market is your suggestion, what would you recommend, and how much do your recommended sights cost? Thanks for the help.