I like the idea - I had thought of something similar myself (reusable/dual-use packaging) when trying to come up with an entry for design slam, but have decided to pursue a different avenue.
The only problem that comes to mind is the increased cost of the heavier packaging, website, etc. that will be passed on to the consumer. Having a higher price than a competing product, even if it is superior, is a tough sell.
Knowing that you can recoup some of the cost later on may help in that area, however.