[bruinaphi]

Like AlphaXiGirl said, there is the issue of having enough. Some chapters are able to wash some of it between parties but it is hard to get lipstick off and the staff have other things to do besides washing rush glasses.

Furthermore, for pref you often need random pieces of china and crystal (for instance, one of my chapters did parfaits a few years ago for one pref party -- how to serve the parfait was a three week debate) and they want different patterns for the plates and silver from year to year.

While the chapter houses are large there is a lot of "stuff" to store and space can be at a premium. In terms of long term planning it is easier and less expensive for the chapters to rent a lot of this from year to year than it is to buy it.