This is what I want to buy but can't justify the money at the current time(or need for one now either). I picked up a used Snap On double flare set at a local thrift kinda store a few years ago. Haven't needed it since.
This is the kind the shop I used to use had also.(He closed and bought a beer store).
I've used both mastercool and eastwood. I personally prefer the eastwood. The rotating head and mechanical action is quick and easy. I also like how the tool mounts in a vice, although the mastercool is easier to use on the vehicle.
I've seen people have success by using one of the cheap tools, but rather than relying on the wing nuts to clamp it down, they instead stick it in a vice. I picked up a cheap one a couple years ago for one project where the line was still installed in the vehicle and couldn't do it that way, but it worked well enough for what I needed at the time.
i have a cheap one and have used it successfully. But I borrowed the eastwood kit from @jims chop shop (James) and fell in love with it. Squeeze flip and squeeze and a perfect flare resulted. If I had to do a set of lines again, I would buy this kit.