Although I'm also a beginner, I'd recommend a DSLR as a first purchase. You'll be able to get started on bright objects (planets, the moon and the sun with a suitable filter) with your dob. Although it can be frustrating, it's possible, and the DSLR has the advantage that it can double up as a day-to-day camera and you can also use it for widefield astro shots with a tripod. If you get heavily into astro photography the DSLR will still be of use.
Here's some examples of what I've managed with a 10" dob and a Canon 550D, you'll almost certainly do better
http://www.flickr.com/photos/malcloc...57630289171018
http://www.flickr.com/photos/malcloc...57630289171018
http://www.flickr.com/photos/malcloc...57630289171018
Keep in mind that you will need a t-ring and adapter to fit the camera into the focuser on your telescope.
Another thing to be aware of is that on some scopes it will not be possible to reach focus with a DSLR, basically you sometimes can't rack the focuser in far enough. My dob has this problem, I get around it by using a 2x barlow lens which allows me to reach focus, and is necessary for a good level of detail on my planetary images anyway. If you get the chance try someone else's camera before investing so you know if this is going to be a problem for you.