Wow. I was also about to post in the Monopoly forum that I don't do the "landing on Free Parking = cash money" thing. What have I been thinking?
The belt does take up a slot and 750 is a lot of gold for low level characters. My group whether I played or DM has always pooled money to get wands for the cleric to use because they cost so much. The item is very good for its price. It allows the cleric to do something besides heal all day, making the class more attractive. It takes up a spell slot which means melee types have to make a choice between staying power and killing power meaning it is not an obvious choice which is something to look at before calling something broken.
I consider wands to be overprice but the law of supply and demand says low level clerics don't have a lot of heal spells so the party almost has to have them. I would pay about 1000 max for the belt because giving me 20 points of healing is not worth more than that especially when the item already takes up a slot. Once you get to the mid-levels a character can take 20 points of damage if the enemy breathes(almost any hit) on them. Someone could by 3 or 4 belts but they would need the money. At low levels the money is not there, and at higher levels it becomes inefficient to do so.