The VAST majority of "Blackhawks" in 44Mag were SuperBlackhawks.
An original "three screw" (no safety) Blackhawk in 44Mag without the word "Super" on there would be worth big money. They had the old-style "flattop" frame - there's no upward-sweeping metal each side of the rear sight body.
Here's a Ruger "flattop" rear sight:
...and here's the "standard" type (same as the GP100, SuperRedhawk and some other Ruger models):
Pics are from the Bowen catalog:
http://www.bowenclassicarms.com/parts_store/ruger_rough_country_adjustable_rear_sights.html
In 2006 Ruger did a modern reproduction of that 1950s-era gun, the "50th Anniversary 44Mag Blackhawk Flattop"...which is...interesting but quirky and likely what the guy is trying to sell you.
Specs:
* 6.5" barrel - good length for hunting and in a good shoulder or "chest" rig it can be carried in the field.
* Blue finish.
* Has the smaller "XR3" grip frame similar to a Colt SAA (and exactly like a New Vaquero - takes any NewVaq grips).
* Based on the "large" frame size.
* Has the cylinder improvements off the mid-frame series that started back up in 2004 - basically the accuracy potential is up there. For any
other large-frame Ruger single action, look for an "underbarrel warning label" (basically "read the instruction manual" and some other junk) instead of a side-barrel as that marks the cylinder improvements on the large-frame series (starting in 2007). The 50th Blackhawk in 44Mag was the sole exception, the first to get the improvements before the warning label location shifted.
(If you see any "read the manual" stuff on the barrel, it's definitely recent production - they started that in...hmmm...around 1980 I think? Not sure!)
* Many folks think the smaller grip frame is "too small" for the 44Mag. This is fixable though. Wood "oversize" grips for the New Vaquero exist, or you could swap the whole grip frame out with parts off of a Super or a Bisley series.
CDNN Investments sold a ton of the 50th 44s on closeout at $450 a pop, and it seems quite possible that's what you're looking at. There's some at gunsamerica right now going for more than $500 in new to near-new condition. Quality on these was very high, collector value is low as a lot were produced, so a lot of people view them as a "starting point" towards customization, doing barrel chops, grip frame/trigger/hammer swaps, etc. They were made during what I consider a peak period for Ruger's quality control (roughly 2004-2007, "vintage years" for Ruger). If you're interested in a 44Mag hunting gun you could do a lot worse as a starting point. Most used SuperBlackhawks were pre-2007 and were less accurate - it's easier to fix the ergonomic issues on the 50th 44 than to accurize a cheaper Super or more expensive Bisley version.
WARNING: the stock grip panels are horrible...nicknamed "the cheesegraters". DO NOT fire full-power 44Mag ammo with those grips on, without gloves. Not even once! My NewVaq357 came with those, and I had to shave most of the sharp checkering off just to fire high-end 357s. You can get good smooth wood grips from Altamont Grips for less than $40 shipped. Options for oversize exist - if you need help finding them let me know but if you have smaller to medium size hands you might like that grip frame size but ONLY with smooth grips that will roll in your hand properly!!!