What is moderately priced? Night sights will run a low of around $80 to as much as $150, depending on brand, style and who you get them from.
Meprolight, Trijicon, XS, Heinie, TruDot... lots of choices, so do a bit of homework before you drop the coin.
If this is to be a carry gun and you already have a holster, make sure that what ever you get is low profile enough to fit your exisiting sight channel... or you may end up needing a new holster.
Shoulder Drive Nicholson Club