This just got discussed in another thread. I think the resolution was that kit parts ending in A and B have been superseded by by the kit part number ending in C.
SK152-24C "Rudder Stop" kit is $565 direct from Textron/Ce$$n
Holy smokes! I remember when I bought mine years ago when they were first released I paid less than $50. I think I paid around $35. for them. I ended up buying two because the first one was missing a couple parts and I thought I would keep the first incomplete kit for spare parts instead of return it for credit.