Your tube amp is important to keep your acoustics running smooth and sounding great.
Keeping the cocktail hour light will also lower the bill. In most cases, half the food that is paid for goes to waste. Even with that, people still eat too much going into dinner and even more food gets wasted. Keep the food to a minimum, literally just enough to give everyone something to hold them over till dinner. As long as something is coming out of the kitchen, most people could care less as long as they have a cold drink in their hand.
For the dinner menu, think just a bit out of the box. A formal sit down dinner will cost a lot more and will tie up the wedding for the bulk of the night. Instead, have what is called a "stations" dinner. The hotel or catering hall can set up food stations around the perimeter of the room and guests can eat whenever they want over the course of the evening. The band can play all night long, people can dance, and when they are ready to eat, they will eat.
Most people try to outdo each other when it comes to a wedding. However, it is amazing how popular the simpler weddings are when all is said and done. After all, the goal is to for everyone to have a good time. Guests will remember and talk about having a great time for much longer than they will a fancy steak dinner.