I agree, a flyby surfer needs all the "info" about the product in front his eyes to make a split second decision to order it (AKA spontaneous buyer)
- with a shapeways render .. well.. not good
You may have sales with shapeways renders only because dice collectors already know what 3d printing is all about and have come to know your other models with their real pics etc.. but not a spontaneous buyer/first time visitor ..
Check on your Google analytics the average time spent on your pages.. 1 to 3 minutes if you're lucky..
I too sell many of my designs with just my own rendering..
(one in particular was a $350 glazed ceramics vase) - most likely because customers have come to know the designer's work by now.
BTW I suggest for any shop owner who uses such campaigns to create a dedicated page for the model - i.e: use a hidden link for it.
This way when you start the campaign you get accurate numbers of exactly how many surfers arrived from your ad, the click ratio and based on your Yippee emails the conversion rate.. this way you'll know how good your campaign is.