Most of the drupal.org infrastructure is currently running on Drupal 6. Drupal 7 has been out for soon three years and the work on upgrading our community home to it has gone on for almost a year now.
Software is expensive because it is irrational and difficult to build. More than 70 years of mostly-failed software projects evidence this fact. Face it, and your chances for success will dramatically improve.
I've been maintaining a growing amount of modules over the years. I am starting to document my observations, habits and challenges, in the hope they'd be useful to other Drupal coders.