Becky, you can easily get used tandems. We got ours, a '91 Burley Duet--I grant we were lucky--for $350 at an LBS that sells both used and new bikes. If you have a local bike club with want ads on their site, I am sure tandems will show up. We can't commute together, but have put 5,000 miles or so on that bike over the last four years.
"My predominant feeling is one of gratitude. I have loved and been loved;I have been given much and I have given something in return...Above all, I have been a sentient being, a thinking animal, on this beautiful planet, and that in itself has been an enormous privilege and an adventure." O. Sacks