Thanks for all of the advice. One thing I wanted to be clear on is that I have 2 x 430EX II's and an ST-E2 transmitter...
Even better. You already have to eTTL flashes, so that gives you some options for either more flexibility, or you could just cut the cost in half. The ST-E2, well, it makes a nice paper weight.
You could either get a third eTTL-equipped flash, like the Yongnuo YN-565EX (or a third 430exII), and then get the eTTL radio triggers (RF-622), or stick to manual and just use the RF-602s. Personally I never use eTTL for portraiture, but some people do and like it. The nice thing about the 622s, is that you can control power from your camera, which is nice for those umbrella softboxes where the flash is inside and hard to adjust.
Since I use manual a lot, I just use my RF-602s. They have a 1/4" thread on the bottom so they screw right into my stands, no cold shoe needed. They’re also small, and I find them easy to use. That said, if I had none and was to purchase radio triggers, I’d probably just get more flexible 622.
The ST-E2 only works on line of sight, which can be a problem when using softboxes. It’s just not worth it given the amount of radio options out these days.
I could drop the price by changing the manfrotto stands, but reviews on amazon are hit and miss on a lot of the cheaper stands. Do your PBL stands hold up pretty well?
My PBL stands feel quite robust actually, but the action opening and closing them isn't the smoothest. But to be fair, I mostly use them for a backdrop, which is to say not much, or a third light stand. I have two Manfrotto Nanos. I love them, but they’re not as big and sturdy as the ones you listed. They’re the gold standard for “Strobists” who want easy portable lightstands. I put softboxes on them and have never worried they were unstable. I know some people swear by aircushioned; I don't really care one way or the other, I just wanted something small and portable. If it's just going to stay in your studio, then you might as well get something beefier. There are plenty of good brands out there, but I've never had a complaint with any of my Manfrotto gear. I don't remember if I said it in my first post: DO NOT SKIMP ON UMBRELLA HOLDERS. I've got a couple of plastic paper weights in my drawer, just get the Manfrotto ones and you only have to buy once.
The other big ticket item is the Sunbounce reflector. It looks portable and easy to use, but I can't say that I have any practical knowledge of reflectors.
Holy crap. I had to look that one up. I’ve never heard of that thing, but I don’t see what it does for $200 that would make it remotely worth it. Get a generic circular 5-in-1 reflector off Amazon for $15.