Suggestions for choosing the musicians or band.
Do you choose the band first, or the caller? Either way will usually work. Some people choose the caller first for a special event, and probably the music first for a regularly held contra. Just remember the caller and music need to want to work together so the dancers have fun!.
Musicians and bands range widely from 2-3 people, to a large band with many instruments. Usually, price will vary with the number of musicians and their experience level. There will be considerable cost savings if you choose local talent.
Expect to pay the musicians, and inquire early in the planning stages about their fee. Dance is largely about community, and what musicians charge for a public, community dance, might be less than what they charge for a private function.
The music for country dancing needs to fit standard 32 measures, but that still leaves a lot of variety from New England contra tunes, to Celtic, even Klezmer music. The musicians should be familiar with playing for dances where a strong rhythm is important.
Make sure you and the musicians discuss the sound system. In a house party environment, you might not need one at all. In a larger venue, you will want some sort of amplification, and sometimes the band or caller can provide that, but may charge extra if they provide equipment and set up. If you provide the sound, make certain you have an electronics expert who knows the room and equipment, and how to make adjustments.