I'm using CarthThrob and a modify by quantity price field (CartThrob Price - Quantity). What it does:
1-3 = $5
3-9999 = $4
It lets you set a lower price as you buy more. Nice feature, but the people entering the data are adding a $ before the prices. You need to enter just the digits: 5 not $5. If the $ is added it breaks the order total calculations. All kinds of weird stuff happens, mainly the effected products are free.
How can I prevent users from entering the $ value? The setting on the field don't let me choose numeric and the CT docs don't mention this little (Big) problem.