Night sights are well worth the extra. I don't know what my old eyes would do without them. As stated before the real benefit is only noticed when it's dark.
I personally have TruGlo TFO's on my XD9sc and I will probably get a set for my G21SF in the near future.
More info: TRUGLO - The World's Most Advanced Line of Fiber Optic Sights
I paid around $78 for the set, and another $40 to have them installed by my local gunsmith.
Absolutely, positively! I have tritium night sights on my Glock 30. Amazing how they glow in the pitch black!
I'm getting brand new Meprolight sights installed on my G20 (service weapon) for $90. I also just bought the tungsten guide rod and a 20lb replacement spring which will help with recoil.