Is there a less expensive scope with the Shepherd style recticle?

It looks like there are a few different styles of range guessing recticles out there. Which ones work or are easier to use?
It looks like you can get a Mil-Dot system on several brands.

The circles on the Shepherd scopes look like they would be pretty handy.
When looking through the scope, at the top and side of the shepherd scope there is a number line. What is it for?
Also what are the small adjuster knobs for?

I've seen a couple of new Shepherd scopes on Ebay for $550ish, is there a cheaper place to buy them?

TIA

The side/top lines are (IIRC) MOA offset between the 2 reticals.

The large knobs adjust the rear retical, the small ones adjust the front retical.

The lower "post" and circles are in the first focus plane, and stay the same size relitive to the target (IOW the 400yd circle will cover the same amount of deer at 3x as it does at 9x)
The crossbar and upper leg of the retical are in the rear focus plane and stay the same size to your eye (the same as most scopes do).

Their "one shot" sighting system works, because as you adjust 1 retical to the bullet hole, you have the other one available to referance the origional aiming point with. Once one is "on", you simply bring the other one over to match up the center point again.

The MOA system Tailgunner speaks of is for rangefinding for tgts. other than that which the reticle is designed for. Once the concepts of reticle-rangefinding are understood the MOA system can be applied more accurately than the circles no matter what tgt. u're after (assuming tgt. size is accurately guessed/measured).

Any reticle that has more than 1 stadia point, dot, line, whatever can be applied as a rangefinding tool with various degrees of accuracy as detailed in this on-line article--

www.ottllc.com/specialtypistols/sp20.pdf
Item C) Reticle-Rangefinding