Well, I've only compared them to what I've used and so far, the GHD's are miles ahead.

They are costly, yes, but they have lasted me over a year so far and still going strong.

Of course, you can almost get the same result from using a steam iron and greaseproof paper, but if you want fast results, not have to go over the same section endlessly, don't want to singe the shyte out of your locks and want reliability- I say shell out for the best.
I use mine for curling too, its faster than waiting for the curling irons to heat up and gives perfect curls.

Just be careful buying off Trademe, lots of fakes around. My golden rules for buying from places like TM are:

1. Look at the feedback. If there is none for GHD's, wait until there is. Let someone else take the first few risks on GHD's.
2. Use safetrader (and pay for it). If they don't agree to it, buy elsewhere. That way you can return it if it doesn't measure up and you get your money back.
3. Do your homework, look for telltale signs of fakes.

Rating: 9/10 I would give it 10 but the cost is substantial.