3D printing through online services can be expensive. For a lot of those services, cost is a function of the bounding volume and the actual volume, plus some handling fees. Scaling the model down will of course make the print cheaper, but hollowing out the model is also a viable option.
Hollow models by themselves aren’t necessarily cheaper. They’ll need escape holes, to free the trapped materials.
I decided to print Pudge, a character from the video game DOTA2. If solid, Pudge would’ve costed $32 from Sculpteo and $22 from Shapeways, not including shipping. After my hollowing, Pudge costed $22 from Sculpteo and $12 from Shapeways, a $10 savings for such a small figurine.
To hollow out the model, in Blender:
1..Delete some faces to create escape holes. I placed them on the bottom of the feet to hide them.
2..Apply a Solidify modifier. This will close the hole in your mesh by created a new layer of certain thickness.
Hope this helps some folks.