Both purchases were big when you add it all up.
Don’t jump to that conclusion.
Overstock was awarded o.biz, which it currently uses as a b2b commerce store, through a request for proposal from .biz registry Neustar. Although the RFP didn’t require Overstock to pay much money directly to the registry, it did have to agree to spend significant resources promoting the o.biz web site. It may sound outlandish, but word on the street is RFP responses to Neustar’s release of one character .biz domains may have included a commitment to spend over a million dollars promoting the site.
Sure, a million dollars is little to Overstock; and if the company is going to promote a new web site it surely plans to spend that much on marketing, anyway. But when it comes to upfront commitment, o.biz was probably seven figures. Who knows, maybe its deal with .co included similar provisions. But they probably didn’t need to be in writing — by spending $350,000 on this domain, it’s clear Overstock is committed to the domain.