The nearest art supply stores are in Helsinki. But if you can't make it to Helsinki, there are several art supplies online stores in Finland that deliver the products quickly, sometimes even within a day.
... and some web shops too:
is in Punavuori, Helsinki, Uudenmaankatu 16.
The 500m2 store has the widest selection of artist and drawing supplies in Finland. https://www.tempera.fi/
also sometimes called Manner, is a web shop that delivers quickly. They have a large selection of printmaking and all other kinds of art supplies.
https://konstashop.fi/
is a tiny art supply shop almost opposite to Tempera, Uudenmaankatu 11, Helsinki. They have a special selection of colours and papers, and enthusiastic and sympathetic service. https://www.diverse.fi/en/
has two art supply stores, one in Helsinki, Lönnrotinkatu 23 and one in Tampere, Hallituskatu 11, and a webshop.
https://arteljee.fi/
is a webshop that has wide selection and sometimes very nice offers. They also deliver extremely quickly. https://www.artshop.fi/
has an art supply store for painters at their gallery in Erottajankatu 9 B, Helsinki.
https://www.painters.fi/en/art-materials-supplies/