Clever Cycles has many Dutch bikes I drool over at least once a month. I must walk in and get my fill.
Isnt there a Jorg and Olif ? They have a steel traditional Dutch bike that has the 3 spd internal gears, a full enclosed chain guard (but it is plastic like Breezer Uptown 8's) and completely rust proof for $495. I know I saw it advertised recently as a "special.
Odering one and having it shipped would likely push it over $600, but at the very least it would have the frame set, bars, and fork you are likely after.
The better model traditional Dutch bikes offered, such as in Clever Cycles, have an internal 8 spd Nexus and some other nice details over the $400 entry level model. They are a pretty penny.
That Nexus hub is well worth at least $300 more. But those bikes are over $1000.
What do you want to do to "customise" these everyday, sturdy, non-sporty-laid-back-style bikes?