It's just a brand name for a specific type of structured soft carrier. SSCs are pretty popular, and ergos specifically are really great quality. For someone like me it 100% replaced the need for a stroller altogether. You'd be surprised about the price thing. For people that full time baby wear you really need to worry about baby's position and strain on your hips and shoulder, a lot of the cheaper ones don't hold up to two years of daily use. For this type of carrier the price is pretty average.
<blockquote><b>Quoting 1inpink2inblue:</b>" The ergo is one of the only carriers that are made to support the baby properly so as to not cause back or hip problems."</blockquote>
Fun fact, ergo-style hip positioning can actuallycorrect mild hip dysplasia in infants. I had it and it wasn't caught until I started walking with a limp. I required years of invasive surgeries, but had they caught it as a newborn double diapering and baby wearing with legs in that L-shaped position may have corrected it. Obviously moms aren't rushing to ergos because of some dysplasia epidemic lol, but it is a great position for any child's developing joints.