Just thinking a little about the acquisition of a good tandem vs a cheap tandem.
I hear so many stories about people who will ride a tandem once, and then give it up. I thought I'd try a tandem with my nephew when he was in town. He just hated it. So much for that idea.
Anyway, if you buy a $100 tandem and really enjoy it, then consider scouring the earth for the perfect bike, or getting a full custom made.
On the other hand, if it is less than enjoyable, then sit back and evaluate whether the bad experience was due to a bad bike, or incompatible riders for example if you can't get your cadence quite right.
Nonetheless, with more practice, the more you'll know about the bikes in general.