It is not as hard as you think. maybe have a look at this: http://www.architectyourself.com/design-your-own-home/
Yes, I'm starting to consider going down this road. Would you say a draftsman can get close to a build cost estimate? Anything to consider when approaching a builder with costings from a draftsman (who obtained them from a costing service). Maybe factor in 20% margin?
Will check out your site.
Appreciate your thoughts.