I'm Maaya it's nice to meet you all =)! I've read posts in the past regarding decotti, but I was surprised no one pointed to Konad Nails, or the nail stampers that are sold in Splendid China Tower at a store called wowwow nails, their site is: http://www.wowwownails.com/
They look something like this:
Their official site for products is: http://www.konadusa.com/
Konad is a korean company that specializes in nail decals and art, so the stamps are literally stamps for their acrylic based nail polishes, I think a starter set with basic colours of red, green/blue, and white costs around: 30$?
They also show demos and do tutorials for how to do it. The lady there is super nice, she'll show you how to mix colours, as well as offer sessions for appointments of doing your nails for you!