The "not for sale" thing fixed itself, but still pretty weird.
However the pricing issue isn't and I have seen the error on multiple pages.
There seems to be a prices difference of $1.50 or $1.78
(regardless of material..?)
For example "Little devil"
https://www.shapeways.com/model/40269/little_devil.html
In the gallery it lists as :
$22.56
When i click on it, the model page shows : $24.35
Another example, the purple tentacle :
On the shop page
https://www.shapeways.com/shops/stuff
it says :$11.46
On the model page $13.25
The problem seems to be restricted to single material objects ?
but not specific to materials ?
Edit : removed redundant info, to avoid confusion.