It's interesting, if you read all the "positive" reviews you'll notice they have the same linguistic pattern, the same wording, etc. Notice how they say "bid responsibly", etc. etc., they all say that. Well if a company is going to have bots to do bidding, to up the pricing, of course they're going to pay their people to write positive reviews too.
If it looks too good to be true, then it is, and bidcactus looks too good to be true. You try to tell me how it makes sense to pay more for a gift card than the actual dollar amount and from everyone I've spoken to that's used this site, that's exactly what happens.
This site is BS, don't do it.