This suggestion would either eliminate the necessity for pro accounts or reduce the price to pay for one.
It wouldnt bother some of us a bit if you put ads on the left hand corner of the page as well as the very bottom of it, below the copyright link.
Also, I notice that there are no ads when you make/edit a new instructable or forum topic. You could put some there.
If this isnt possible with you guys, or you just dont want to do it, I understand. I am not against pro accounts, But some others are, and I cant really afford one myself (I cant even get a stinkin job due to child labor laws).