I love the Gerber organic onesies for our son.  They are sewn much better than a regular Gerber onesie (we own both kinds) and the fabric is much softer.  I think they're well worth the price, even though you're getting only 4 instead of the 5 that come in a pack of normal onesies.

They do seem to run a little small, but with owning the same shirts in both organic and regular, I think it's because the regulars are made from stretchier material.  The organics have a thicker knit that isn't as stretchy, so it seems to fit smaller.