Well, I work at a school that just got a 3D printer and I sweet talked the teacher into printing this design I made. I really just wanted to test printer and see and feel what a 3D printed object is like. It's much more stiff than thin pieces of Instamorph are. Of course it allows for quite a bit more fine detail. Instamorph mostly sticks to this 3D printer PLA plastic. So, my plan (once I learn how to use the printer and get some decent prints) is to really utilize both materials into the playsets - the results will still be all plastic.
I did price the chair out on Shapeways and a couple other printing services - they wanted anywhere from $40 - 80 just for the chair. Clearly I figured I'd be better off biting the bullet and buying a printer rather than getting pieces done professionally. I figure the chair likely cost around $3 - 5 for materials.
I've used 3d software for many years now (I've been a video production teacher for 15 years) - so I don't have too much hurdle to jump through to be able to design things to print - it will just be the actual process or printing (well) I really need to learn how to do.
In the end I suppose I'm picture still using Instamorph to do landscape type pieces, whereas 3D printing can provide detailed, evenly designed pieces (such as guns, chairs, walls, floors, consoles, etc). I'm bubbling over with creativity at the moment - just wish the printer was here, it was in good working order, and I had hours and hours to dedicate to playset making