I don't know where Gilmax is (I think he's kinda shy

, either that, or he's gettin' his butt kicked workin' on his website) but he suggested an idea to me yesterday that seemed really good, so I'll go ahead and post it here before either of us forget it. Currently, the ability bonus granted by a magic item taps out at +6, but Gilmax suggested that a sliding scale (he really likes those) might be more appropriate. Basically, the higher the bonus, the higher the cost calculation formula. It would look something like this:
+2 to +6 - bonus squared x 1,000gp (this is the formula in the DMG and T&B)
+8 to +12 - bonus squared x 2,000gp
+14 to +18 - bonus squared x 3,000gp
+20 to +24 - bonus squared x 4,000gp
etc, etc, etc.
So, while a Belt of Strength +6 is a meager 36,000gp, a Belt of Strength +8 would jump to 128,000gp and a Belt of Strength +10 would be 200,000gp. Likewise, a Belt of Strength +14 would jump to 588,000gp.
How's that look? (Thanks Gilmax

)