How about a steering tube extender?
I also have back issues (arthritis) and need to ride in a more upright position than my road bike offered in its stock configuration. My LBS installed a steering tube extender and spacers, plus a different stem, and this brought the stock handlebars up to an acceptable height. Not sure if that would be cheaper than the dumbo bar, or not, or provide you with enough height, but it might be worth checking out.
2011 Jamis Quest "Cy"
2009 Trek 7500 "Diesel"
2008 Rans Stratus LE recumbent "The 'Bentley"