Kitty's prices are pretty accurate (you could safely bump them up several hundred thousand or a mil) but I think the coloured/shaded pieces should definitely be priced higher! :< That's where your art shines best I think. ;o
(they're super adorable and I LOVE the colouring style)
For a coloured and shaded headshot, I'd say at leeeeast 5m.
For a coloured and shaded fullbody, I'd say at leeeeast 10m.
Note that these prices are not accounting for the time you put into these, so remember to include that into your prices. Takes you 10 hours? Then 10m doesn't cut it >:U
Hope that helps uvu <33