AAA's (2 each) and Smart Media Cards.
It doesn't seem to eat batteries, but I'll pick up some NiMH rechargeables anyhow. These and 9V NiMH ($10 each) for the Nady will doubtless save bucks in the long haul. Also on my list is to grab a higher capacity 9V NiMH Radio Shack race car pack ($25) for the the Nady and the Hobbytron 7W amp and Specos, should they ever arrive.
Last time I was in the local Target I saw SMC flash cards for $40/128MB; I think they're common to digital cameras. Which is something to look for in a digital camera, as well, since I love a good two-fer whenever I can find one.
Which gets to why I went with this arrangement rather than a commercial caller myself. It's more than just a two-fer, more like a four-fer: it's a)a predator-caller, b) an itty-bitty field recorder for digital capture of animal sounds in the field with an external mic, ie the Nady c)a note recorder that also works with it's internal mic d) an MP3 player that I can cleverly conceal in my pocket and actually listen to tunes! (okay guys, let's see you try THAT with one of those all-in-one commercial jobs, just to try to get a new camo'd Foxpro or Loudmouth or Predation job past airport security /ubbthreads/images/graemlins/smile.gif
Also, if or when something better comes along next year I won't be out $300-600, just $100. Easy enough to upgrade the player later on.
I'm not a gadget freak, particularly, and tend to stay with older stuff as long as it still works... but already this is just soooo much better than the old cassette player (BTW, my first one was a Panasonic that recorded too that also cost $100--15 years ago!) or the CD player (which involves running 40 miles to the office to burn a new CD) that the learning curve is actually kinda sweet and therefore not so steep after all.
-LionHo