If you want people with home printers (as in Thingiverse) to be able to print it, you'll have to go thicker than 0.5mm
My home printer just ignores any wall that is only 0.5mm
The big thing about the thickness at Shapeways is to also consider how long the part is. I have a model in FDP - a rounded end cylinder with 0.3mm walls.. it was 30mm in diameter, 200mm long. With walls that thin, and no internal supports, it cracked like an egg. Since then, I've never used less than 0.5mm for things that large, but I tend to go on up to 1.0mm. One patron told me that at 1.0mm, FDP directly competes with the strength of injection molding.
To avoid warping on long sections, you should add some internal supports, even if they're designed to be removed.
See this model for example:
https://www.shapeways.com/product/RV5LCBFJK
It has 0.5mm walls, and those inner supports are 1.0mm
The thing that's going to hurt on houses like the one you have shown is the support material. If the base of the house is not flat, then it consumes more support material. If you can, I'd split that model horizontally at the foundation, separate off the gazebo, and print it as three pieces. You're still going to pay a lot for support material on the main house (unless you also make the roof a separate piece) but you could reduce the cost for the irregular base on the foundation.