It is only expensive if you don't shop carefully for your grafting products. I think NE Seeds is reasonable for the RST-04-106-T root stock seed and for me they are near perfect because they are tolerant of FFF, RKN, and BW. All of those are killers here. I wait to graft until my root stock are large enough to root the top portion to use later in another batch. Link below.
The most expensive thing annually is the larger grain DE from O'Rielly Auto Parts that really helps with the success of the healing stage for me. It is reusable so after the first bag it can be a while before I need another. Another big cost but one I recommend you incur is getting a good selection of grafting clips from 1.5mm to 2.8 mm. They are not so expensive but you have to buy 100 of each size but since they are priced at less than a nickel apiece it works out to about 5 dollars a bag per size plus whatever the shipping is. They also have an amazingly low price on tomato clips but you have to buy a lot of them. I have been buying mine from Hydro-Gardens here is a link to their grafting clips.
https://hydro-gardens.com/?s=grafting+clips
You could get some clips and just practice with any cheap seedling this fall and by winter be ready to start for real with the good root stock. I practiced like that until I got fairly good at the mechanical part of grafting. It was the more subtle things that I had to figure out to get my survival rates up in the healing process. I posted it a while back and though it seems a bit of bother it does make a huge difference in the success rate for me.
Bill
Bill