OK, car is a 99 Miata. Question is, how difficult is replacing the ball joints on the car? Had a chance to get the car on a hoist earlier today and found some issues that need addressing soon. Looks like the hardest one is the ball joints, they're worn. Also worn tie rods but I've done tie rods on different car so I know about those. Never done ball joints before. Would it be easier to just replace the A-arms that have good ball joints or replace the ball joints on the car? Also have a cracked anti-sway bar mount but that looks easy to replace. Could explain why I have slowed up a bit autocrossing. Or at least that's what I'm telling myself. 
Lower ball joints are easy. They just bolt into the lower arm. Uppers are part of the arm, you can't replace just the joint.
You can get good, used upper arms from planet-miata.com for around $100/set, as opposed to $400ish new.
I'm about to order some so I'll have a spare set around when I do the suspension refresh on my '90 this winter.
The Parts Group is real close to me and I know the guy that runs it. He's done work on my Miata and I've gotten parts from him. He's working on getting me what I need. The swaybar mount broke while autocrossing yesterday. Made the car very loose and couldn't keep up with the leaders like I normally do. At least that's my story and I'm sticking to it. 
