I've been using common Remingon 'Sluggers' in my smoothbore 12 gauge. Now I see there are a number of sabot rounds available to extend range...at about 4 bucks+ a pop which is kinda of making me hesitate. Is it possible to reload sabot loads with some basic reloading equipment? Utilizing a Mec 600 press or the old Lee Loader set-up?

BPI sabot

BPI sabot and 350 gr. 50 cal bullet

You will need a fully rifled slug barrel to shoot any sabot. The plastic sabot grips the bullet, spin is imparted to the bullet inside the sabot.

I just got interested in these NEW sabots from BPI. I just got all the stuff to load some 350 grain Hornady XTP bullets which will leave the barrel at a claimed velocity of 2350 FPS! I did a work up of the cost to me, $1.05 per shell!

As mentioned, you need a rifled barrel for sabots. If you want to reload and have a smoothbore, about the only thing you can do is use either the Lee or the Lyman molds for slug rounds. They use a standard shot cup. I used the Lee slug for a few years but was not completely happy with the accuracy or lethality, and after an extensive journey I now use the BPI "Dangerous Game" slugs.

Of all the reloading I have done, loading slugs has been the most hair pulling in regards to tuning for accuracy.

Oh yeah, you will have a bunch of options if you check out Ballistic Products offerings.
http://www.ballisticproducts.com/