As Matt noted, the OnLine blades are sold by both JGR through her studio and website found here: https://intarsia.com/collections/scroll-saw-blades or at Seyco’s site found here: https://www.seyco.com/blades/ (Seyco also sells Olsen blades.)
JGR sells them by the dozen or a gross and you can mix and match sizes to get the gross. I think you may also be able to mix and match the Gold, Platinum, TLB, but not positive on that one. (you can reach out to Stacey her office manager who does the orders usually and ask.) They have a toll free number you can call. Looks like Seyco will let you mix but have to stay in same “group” like all Gold, all Platinum, etc.
One note, While JGR pretty much strictly does Intarsia, I have used these blades for all kinds of Scroll Saw cutting, not just Intarsia so they do work well for other things. However, like JGR notes on her FAQ section in the Blades discussion - “The kind and size of scroll saw blades can vary from one user to the next. What works for me here in the studio may not work as well for you on your saw. I have a certain “feel” that I like when sawing and that can be different than what you like.”
I checked my packaging on my blades and on both of their sites and it does not identify them as anything but Online blades so I do not know who manufactures them for them. On Judy’s site, if you click on each blade type, it gives you some different charts that show the blade width, thickness, TPI, etc. for each size. She also shows recommended blade size for different Wood types based on 1” thick. In her FAQ section, she has the following info. that explains the different types of blades and what woods best used for: (found here - scroll down a little to blade discussion)
https://intarsia.com/pages/faq