Find fancy decanters in cookware stores, catalogs, or online to package this vinegar and give as gifts. Tie a glittery ribbon around the bottle and attach instructions to use the slightly sweet vinegar dressing on fruit and green salads.
In a large stainless steel or enamel saucepan combine cranberries, vinegar, and champagne. Bring to boiling; reduce heat. Simmer gently, uncovered, for 3 minutes. Remove from heat; cool. Pour mixture into a clean 3-quart jar. Cover jar tightly with a nonmetallic lid (or cover with plastic wrap and then tightly seal with a metal lid.) Let stand in a cool, dark place for 2 weeks.
Strain vinegar; discard cranberries. Transfer strained vinegar to decorative bottles. If desired, add a few additional cranberries to each bottle. Store vinegar in a cool, dark place for up to 6 months. Makes about 6 cups. (Nutrition facts are for 1 tablespoon.)