I could understand if some tracks that were especially long or were rare / live cuts cost $3. I personally would likely never buy one however, just as I don't buy $30 CDs with all those "Bonus Features" and crap.
Furthermore, while I would support the increase in cost for DLC over time, if it were to happen now, I'd be rather disappointed as the market is still very poor and the vast majority of industries are still in hiring and salary freeze. I would think HMX and its partners would understand that and offer more enjoyment at profitable prices (as they are) until such an upturn in the economy allows the standard consumer to adjust their budget accordingly.
Not for nothing, but food prices and prices for general services have actually gone down in most parts of the country over the past 18 months, and they haven't bounced back yet because people just don't have a ton of money to spend.