Marty,
I got night sights for my M9-A1 from Trijicon. If the sights on your L series Steyr are dovetailed in (I know that the M series are) then there should be no issue having someone install them. You can also call Trijicon and ask them if they will work with your gun. They take 6-8 weeks to come in. Planet Optic also sells Trijicon night sights at a lower cost than Trijicon directly. Here is the link to the sights on the Trijicon website..
http://www.trijicon.com/na_en/products/product3.php?pid=ST01
I got night sights for my M9-A1 from Trijicon. If the sights on your L series Steyr are dovetailed in (I know that the M series are) then there should be no issue having someone install them. You can also call Trijicon and ask them if they will work with your gun. They take 6-8 weeks to come in. Planet Optic also sells Trijicon night sights at a lower cost than Trijicon directly. Here is the link to the sights on the Trijicon website..
http://www.trijicon.com/na_en/products/product3.php?pid=ST01