an inspiring story and great to hear - congratulations, very well done!!
AL, you're keying in to some serious truth there. Of all the pre-requisites for a sellable/great picture, the gear it's been produced with comes surprisingly far down the list.
There are camera+lens combinations that can produce "technically more correct" images than the D60+any lens, but when you think about it, how often is that a selling point for an image?
I'd go as far as to say that the vast vast majority of images that are sold, are because of a great concept, composition and decidedly INcorrect color and clarity.
If you as a photographer have something very very specific in mind that require shooting under circumstances that lie outside the D60's performance envelope, then indeed a D700 can perhaps fill the gap. But those scenarios have to be very specific.
If the pure ambition is to take "better pictures", it's likely that painting class is going to make more of a difference than another piece of gear, for example.
For Neil, I think that sheer determination and the entrepeneurship of getting the images out there so they can be sold, is a big part of the success. There are billios of pictures out there that will never be sold, simply because people never see them. Marketing 101 one might say.