They are one of a kind, special made for Honda and I can get them directly from the manufacturer but I have to buy hundreds at a time and there are 2 different sizes (thousands of dollars just for a minimum order). I did not see a big enough need at the time to make the order.
What I do is scour the classifieds for low mileage stock takeoffs radius rods (they take the same bushings as the knuckle) and snag them up for spares rod ends.
The inner joints that were attached to the frame will fit the knuckle (and every other joint except the outer radius rod ends).
The wire clips are a little tricky but if you have 2 sharp little picks, it is easy. Hold one end of the clip towards the end and use the other pick to spin/compress the clip while slipping the pick under it and it will come right out. You basically use the sharp ends of the pick to grab the clip and compress it smaller so it will come out. After a couple tries, you will become a pro at it