All I can say is that I hope you've spent some time searching this forum for posts directed to new tandem riders and those considering buying a tandem.

There's absolutely no need to re-create the wheel here. Go find and read them and you'll gain an incredible wealth of knowledge. Someone in your position would be remiss not doing this.

That said, I hope you can get your questions answered about the specific tandem you're interested in. There are a lot of inexpensive tandems out there, both new and used. But you'll have to know where the point of diminishing returns is. A tandem has a lot of demands placed on it, so if you go too cheap, things can be dangerous and fail. Brakes failing, for example, is catastrophic and potentially deadly for you and your riding companion.

The best bet is for the informed shopper to find a great deal on a used tandem. My '92 Cannondale road tandem, for example, would be a GREAT used purchase for someone new to tandeming. Why? Because it's very high quality, in GREAT shape and would be a bargain price. 25 year old used tandems simply do not bring a good resale price for the seller; but they do present a great deal for the buyer. But the knowledgeable buyer who knows how to spot quality and avoid damage and pitfalls. But that's IF I were to decide to sell it; but I'm not. But there are lots of bikes like this out there. It just takes the knowledgeable eye and luck to find it.

Good luck!