Everyone should work within their budget, as going overboard can cause lots of stress. Does your friend have the proper equipment? Good sound system with speakers that will work properly so everyone can hear and have a good time? A microphone so toasts can be made and everyone hear?
Professional DJs are not that expensive and truly worth the price ($450 and up). If you need to cut back somewhere, considering going with less expensive food and beverage choices. Forty percent of wedding budgets are usually spent just on the food alone.
If this is not an option, then consider that a lot of high schools have very good sound equipment for their school dances, and often the student councils provide their own entertainment due to tight budgets. You might call around and see if you can hire a local school DJ in your area. Copen Cabana DJ Audio Visual Production providing Custom Wedding Coffee Table Photo Book with DVD Services http://www.knowareland.com