Upload & Sell: Off
For the record I have a D3s as a backup and I got a really good deal on a used D4. I can likely sell it in 2 years for what I paid for it, and any money generated will be gravy. I had a D700 as a backup, now my wife second shoots with it. I shoot weddings and events just to pay for my equipment and to give my wife some spending money. I am fortunate to have a job to cover my other bills. I usually shoot weddings with a black shirt, tie, slacks and dress shoes. I have not ever worn a tux to shoot a wedding, noone has ever asked me to, but it seems that this venue, its managers, it's customers, and probubly it's guests want to be dressed to a higher standard.
Talk to them, if they do not care that you are dressed smart casually, wear smart casual. Maybe they just don't want you showing up in Jeans and a Harly Davisdon tshirt. If they insist on your wearing a suit, you should do that.
In the 80's I assisted at a wedding in Boston where the customer was a million dollar a year surgeon, his newphew was a famous rock star, and he rented out a whole floor in the most exclusive hotel in Boston. I was asked to wear a tux because the company I worked for wanted all their emplyees to wear a tux to make a good impression. I know things are more casual now, but if the event location values wearing a jacket, and you show up in a tux, and the customer your client lets everyone in the sales office know how you exceeded her and their standard by wearing a tux, and all the clients friends see you wearing a tux and are impressed, just maybe you can get some referred business from the event. If disapointing the event location is not important to you, wear whatever is comfortable. It is usually a long shot to get referrals from event locations anyway.