Ron Thomas Case
If you are sure it is in fact an actual genuine Ron Thomas leather 2x4 case then $120.00 is a ridiculously low price and if its in good condition I would jump all over it. I own a dozen of Ron's cases in both 1x2 and 2x4 configurations and I can attest that the information Poolrod posted in response to your question stating that Ron gets $375.00 for a 1x2 leather print case with no pocket, handle or shoulder strap is 100% accurate.
It is not very common to even see any of his 2x4 cases for sale on the aftermarket and I would venture to guess if you did find one it would sell for anywhere from $300.00 on up depending on its condition and what material it was made with.
Ron makes cases that can sell for upwards of $1500.00 or more if they are fashioned from an exotic material like Zebra or Elephant Ear. I saw one he had displayed at this years Super Billiards Expo back in March that was a 1x2 made from Giraffe and was absolutely gorgeous, if memory serves me correctly I believe it was $1900.00 but don't hold me to it because I could be mistaken, I looked at so many items its all a blur at this point, LoL!
Like Wedge had posted, if you remove the cap he will either have his name signed inside it or on some of his older cases his name was stamped inside the cap.
I personally bought one a few months back that was a black lizard print with a 10" pouch and side carry handle in like new condition and I paid over double the price you mentioned and feel like I got a fantastic deal so if you can verify it is a genuine Ron Thomas case and its in nice condition I think you can't go wrong paying anything under $300.00.
Hope this helped and if you don't want it have him send me some pics and I will buy it, LoL!
Ken