For a Dj you will find a "WIDE variety in cost" as well. You get what you pay for. You want to be sure they have back-up equipment, are insured, etc etc. Also, alot of times when you first meet with someone to talk to about your wedding... they are NOT the person who will be dj'n your wedding. Most bigger operations have several dj's on the payroll. If it matters to you, make sure you ask who personally will be doing it. You should be able to get references also. Another thing when you say "no country, no hip-hop/R&B/rap"... that will most likely shorten the length and liveliness of your reception. You may want to think of just asking it to be kept at a minimum and/or later in the night. How long in advance are you booking your dj? Most good dj companies are booked anywhere from a year to 2 years in advance. You can easily drop 1500.oo on a good quality dj. Heck I know some that are double that. Like I said though you do get what you pay for. Oh and most good reputable companies will have a portfolio of previous jobs they have done. Can be a good idea to ask for that and take a look. Shop around too. The dj runs everything after you leave the church/ arrive at the hall. You want to be sure you get the right one. A bad dj can ruin a event!
any other questions just hollar.
EDIT: oh yea depending on how in-depth you want to get you can register over here http://www.djchat.com and post that you are looking for a dj and the area. There are some good ones over there.