Hey Duck,
I recently bought a Buckmark Lite and went with a red dot reflex sight from Tru Glo.
I bought a rail from TacSol that has the rear sight included. $70 IIRC...
There's cheaper units w/o the rear sight if you want to go that way.
You remove the top rail from the BM and replace same with the new TS rail.
Sight that in as a back up in case the red dot ever fails.
The Tru Glo sight is not expensive, $50 - $75 depending on vendor.
It clamps to the rail. Sight in is easy.
It will show you just how much accuracy your leaving on the table with iron sights!
Here's some pic's...
The targets at 25 yards and shot right after I sighted in the new red dot.