There's only one way to go with a flash IMHO: LumoPro LP180.
It's a manual flash, so no TTL. It's also the best damn speedlight on the market. Best of all, it's $200. It's the flash that many top names in the industry use, and it's build quality is second to none. I have two of the previous version (LP160), and they're great. Why do I have two? The first one was submerged in a foot of water and I thought it was ruined, so I bought another one. Guess what? That was 3 years ago, and after it dried out, that flash still purrs like a kitten. I've also seen one get run over by a car and still work.
Try that with those Yin-Yang-Yong flashes. Ain't gonna happen.
I can't in good faith recommend a "rock solid" setup on that budget. A good tripod head will cost you that much.
I really like the LumoPro units also, but there is a time most of us have a need for on camera/TTL and if you can afford only one unit it should probably by Yongnuo or Nikon if budget permits.
Tapp'n on the go