Instead of buying a separator, if you have an Autozone nearby, you can rent the tools you need for free. That's what I did when I had to do suspension work recently. In essence you pay for the tool upfront and they'll refund it back to you upon return. I believe I ended up using a tierod end separator that worked on both the tierod & balljoint.

I've used a pickle fork before too and that would work fine. You don't have to worry about ruining the rubber boot on the old balljoint since you're replacing it anyway.

Good Luck.