As mentioned by other commenters, the Creator series has sets with more generic pieces. And you can easily buy large quantities of generic pieces, at least in t

As mentioned by other commenters, the Creator series has sets with more generic pieces. And you can easily buy large quantities of generic pieces, at least in the US. For instance: http://smile.amazon.com/LEGO-Classic-Large-Creative-Brick/dp/B00NHQF6MG/ref=sr_1_10?ie=UTF8&qid=1424758013&sr=8-10&keywords=lego+bricks http://smile.amazon.com/LEGO-Classic-Large-Creative-Brick/dp... And the City series strikes me as striking a decent balance between generic and speciality pieces.