Underpriced.
As noted previously, it's listed at 500 GP to Create (thus a 1,000 GP Market Price).
As it also notes a 40 XP (Correct with 500 Creation, but not 750 Market Price), I'd go with 1,000 as the Market Price.
Which seems better to me.
As it takes a Belt Slot, I know almost all of my players have a better item in that slot by level 10 or so.
In my games, it would become the Band-Aid after the Battle.
Take Damage? Just Slap on the Belt, blow a Charge, replace it in the Bag of Holding.
In my games, I'd prevent that this way.
It must be worn by a living Humanoid for the 24 hrs prior to Dawn for the Charge to Refresh.
I'd call it the Magic augments the natural "Life Energy" in living Creatures to Power the Charges.
Thus, no Band Aid.
In fact, they'd probablly give it to a Cohort or Follower. I really good item for a NPC.
(Or they'd take a Goblin Prisoner, make him wear the belt & take it off him to Expend Charges).
But, all in all, I'd call this an excellent Low Level Item, that can continue to be of use when the Players get to high Level.
PS. For noticing the Pricing Error, Mistwell you'd get a 150 XP Bonus in my game.
As a Duly Appointed DM for the Inner DM Circle, feel free to Print this out and tell your DM:
"See. This random guy (at least he says he's a guy) tells you to give me 150 XP, since he's a Duly Appointed DM."
(If you have enough Ranks in Bluff, he might buy it).