Matthew, very interesting question. I hope more agents will answer.
I think Broke's answer boils down to "ripoff merchants" and it certainly sounds like he did encounter one such. Although the initial quote does not sound too far off the mark for a quality web site.
But I am also confused... you would never attempt to build your own house or car? Why create a "do-it-yourself" job out of something that you hopefully have discovered is the most mission critical part of your business? It is easy for me to see what web sites are home made and which are not - granted it is my profession so I might be more observant than others, but some of your clients will surely also be able to see this as well?
Would you trust a mechanic, plumber, carpenter, builder who had clearly made his own tools? | 
