Been reloading Pistol rounds for 20+ years. Been wanting to reload 20/12ga rounds, But have no idea which reloader is best for the money. I want to reload mostly buckshot/slugs and maybe some steel shot. Any help w/ this would be greatly appreciated. Thanks. Oh 20ga 2 3/4" and 12ga 2 3/4-3".

I would start with a Mec 600JR and start loading bird shot to get the hang of it. Slugs and buck take more effort.

Your talking about starting at the advanced level if you want to load steel and slugs. You would be wise to read allot first. Start at Ballistic Products and get some books first.

I have one word for you...
MEC.

Good used MEC reloaders are always available and are a great value for the money. My personal favorite for low volume rounds is the "Sizemaster".
Since you're an experienced cartridge loader...I won't get into the standard SAFETY chat. I will add however.. With shotgun loading...just like anything else, WEIGH your charges when starting out. Make sure you're getting what you think you are from that "volumetric" charge system. DO NOT fall into the trap of using powder bushings without checking for accuracy and precision.
It's hard to believe...but over the 30 yrs or so that I have been actively involved in shotgun competition, I've met a few guys who just loaded "by bushing number" ....didn't own a scale, and had no idea how much powder was in their shells. These were also (usually) the guys who didn't know why the primers were being blown out of the back of their hulls...!!

I use the MEC Sizemaster.It will last a lifetime.

I agree with the MEC recommendations. Their equipment & product support are excellent. You might try lurking for a while on the shotgunworld.com website. There is a wealth of good information there.