Some are done by hand? I thought amiibo's were lauded for being low quality?
They're not low-quality; for the price, they're solid, well-presented little figures. Some early ones seemed to have quite variable quality control and odd decisions (the different colours on the supports, occasionally wonky paintjobs, manufacturing glitches) but the most recent waves are solid and attractive.
"Done by hand" almost certainly means a worker has spraypainted them using stencils and masks, not that they've gone at them with and airbrush and spent ages on each figure.
There's a fair amount of hyperbole about how bad amiibos are from the discerning action figure market, including claims that stuff like mass produced World of Nintendo figures are articulated and look better than amiibos, for cheaper. Apparently, it's not true.
Here is the World of Nintendo Link, which retails for $10 to $20:
Here is the non-prototype production amiibo Link, which retails for $12:
The WOW Link is articulated in a few spots, and some people may want articulation. However, the amiibo is more fine-grained in terms of molding, better paint finish and surface texture, and is a lot more on-model with the Link it is referencing (Smash 4 in-game character and trophy pose). Link is also one of the simpler amiibos with fewer parts and a limited color scheme. The official Bad Amiibo is seems to generally be considered Marth. Characters like Dedede look nice and have elaborate, nested construction.
If someone wants very good looking figures that are also articulated, you go up to the $40-$60 dollar range. At that price, the figures should look really great and be perfectly on model. I suspect the idea that amiibos are low quality rip-offs is coming from the crazy scalping market which has spoiled the figures' intent as affordable twelve dollar smash trophies anyone can have in real life. It's as if they're seen as competing with Figma and such because of how much some people with money to blow are paying for them.