I'm also a self-taught geek, and now I am part of a Drupal/CiviCRM shop with three other folks, all self-taught. We do very well, and just made a job offer to a fifth person, also a self-taught Drupal dev. Here's some thoughts from the other side of the interview table.
A few thoughts:
* Getting hired in the Drupal world as a self-taught geek is way easier than in most corners of the IT world. There's lots of small employers, and there are ways to demonstrate your skill that don't involve certs.
* Drupal is a fast-moving product - we want to know that you know the latest tools. Have you developed in Drupal 7? If you're doing theming/front-end, what's your experience with Sass/Closure/etc.? Basically, if you're not plugged into the Drupal community, it's difficult to be up-to-date. So YES, go to DrupalCon, Drupal meetups, etc. - and make sure your prospective employer knows it (if you're looking to get hired by a Drupal shop)
* The most important part of being hired is networking. Not what but who you know, etc. Another reason to hit the Drupal community gatherings.
* I'll echo what other folks said about needing a portfolio. If you don't have one, make one. Seriously.
When hiring, we asked for folks' Drupal.org usernames, and we looked at their history. Seeing that you've made a non-trivial patch to a major module counts for a lot. Seeing that you know how to make a comprehensive and useful bug report means you'll get better responses when you're working on our projects. We asked about community involvement, as a measure of a) seeing how up-to-date folks were, and b) determining if their contacts in the community will help in a pinch - our good relationships with key Drupal devs has certainly helped us in emergencies. It also means we've been referred work (particularly because we specialize in Drupal/CiviCRM). We looked at portfolio - especially important if you want to be a themer.
Finally - one problem we had with hiring folks in your position was a lack of experience with tools used for working in groups. Familiarize yourself with at least one of the popular project management tools used in the Drupal community (I'd suggest Redmine, Open Atrium, or Basecamp). Learn git. Brush up on CLI tools like drush and ssh if you don't know them already. I think it's telling that the person we offered the job to was self-taught, but was already working in a small shop. A self-taught person with experience with the tools I listed above would have closed the gap that advantage brought to her.
One more thing, I guess - there've been a lot of good arguments for self-employment on both sides of the debate in this thread. Consider the middle option of being semi-self-employed. Moonlight doing Drupal dev. I moonlighted as a freelancer, and brought my day job from full time to part time to gone.