Not just "why would we?" but also "How the fuck could we?". Even Gox wasn't around then so if you weren't mining them, it was damn near impossible to buy any, especially from within microscopic communities outside the US. Heck, back then you might have been the *only* person in your entire city to be interested in it, so even localbitcoins.com wouldn't have been practical.
IIRC, people were happy to do PayPal trades at the time (the community was less scammy in hindsight at the time) so that's how people managed to 'buy' them. That being said there were far more people (but still nothing in comparison to now) just trading stuff for them. But yeah the volume of trading then was literally nothing - far too new and experimental for all but a few to jump wholeheartedly in.