ChartsForWorship.com is one of at least two sites which specialize in full orchestrations, besides offering lead sheets. You can browse their listing of available songs by title or by album. Icons abound to preview clips, or preview or buy lead sheets or orchestrations:
ChartsForWorship Title List
An interesting link on the site is to Jason Yarbrough's site, which lends other helpful resources: soundtracks, Praise Hymn's recording packages, and more:
Singer's Club
If you're a member, and purchase the Featured Chart for any week, you'll get another (equal or lesser value) free.
www.chartsforworship.com