i know most of you guys are into the higher end of optics, mounts, risers, etc.  but i'm looking for an inexpensive way to mount my dad's BSA (?) red dot unit on a flat-top AR-15.  he has fairly bad eyesight, and doesnt want to spend a lot of $ on something like an aimpoint when the BSA seems to work well enough for him.  anyway, i just helped him update to a new upper which happens to be a flat top and no carry handle.  is there a reasonably inexpensive riser block/whatever which allows the BSA to be mounted up high enough to be the primary sighting system for him?  

TIA...

ck out CMMG Look at the 18th one down when you get there.  Just click on the CMMG in color.
They have a riser that should work.