Depending on how much they cost as well as how much IKEA wants to profit from their sale, it could be well within their reach to charge (for example) Americans what one would expect for an IKEA garden shed, writer's shed, whatever you want to call it. If you search prefab outdoor sheds on Sears, you'll see that prices vary from around $300 to $2000 depending on size and materials and taking sale prices into account. One advantage IKEA has is that they thrive on people
buying in to their systems, even when it's not necessarily cheaper than the alternative. That can be attributed to better design, integration/continuity (i.e. "everything just goes well together"), or just shopper's fatigue after a day of wandering through an IKEA store. How much would you be willing to pay for it? That's the only question IKEA needs an answer. If the can sell it for cost x 2 without an average IKEA shopper batting an eye then they're golden. Whether they want to try squeezing a profit in there is up to them but by no means necessary. They get publicity and a new product line.
To address what you've said about OLPC, I don't think it's a good comparison at all. Problems with the OLPC in this case: huge restructuring due to the economy, never intended for consumers, and in an already massive product field (PCs > Laptops > Netbooks). Still, the Give 1 Get 1 campaign netted 83,500 sales. That's pretty good, considering the cost was $400 in the same year that the MacBook Air became available for $1800 (which people thought was pretty high then). How many of those people expected to actually use their OLPC? How many people do you think would buy an IKEA shed just for it to sit around and make them feel charitable or something?