Here is a charger with 8 D-cell batteries for $40 - http://www.all-battery.com/t-1199buniversalbatterychargerwithtimercontrol8nicdd5000mahbatteries.aspx
I can't say as to how long they'd last.
I've used AA in my camera for years - I think longevity may depend more on how often you recharge them than anything else. The 6-volters we use on our Moultries last 2-3 years and cost us $14 each which to me is a pretty good deal.
I know I just asked this question...But didn't see your post. Do you know where I can get some rechargeables at 5000 mAH capacity? I have 2500, and have had problems with them losing power fast and not triggering as well...especialy in colder temps.