Prices can vary wildly for no obvious reason, Mike, so be careful not to over-order - I assume on a student's budget you don't have as much disposable income as some of us.
I ordered 10 tan and 10 brown satchels, and one came at 13p a unit (reasonable) and the other at 65p a unit (5x the cost). I even rang to query this after someone pointed out the wild variance, and they told me that's just the way it is.
I wanted lighter-coloured satchels to put on Union soldiers and darker ones for Confederates, but now if I need more I'm going for the cheaper option.