Soffit vents and roof vents vent the attic of humidity and excess heat. Cellulose is the lowest cost insulation. A minimum of R-38 is recommend. Ceiling insulation is critical because heat rises and takes the path of least resistance. Low, or non-VOC paints are readily available at little or no extra cost.
Latex paints are easy to work with.
Doors and face frames are solid wood. OSB is used on the interior. Doors could be simple slab doors out of glued up boards. Finishing touches should reflect timeless, natural, durable qualities. Inferior mass produced cabinets will destroy the aesthetic design.