I've long been a fan of Priceline. I've lost count of the number of hotel rooms I've reserved for a fraction of the listed price both in the US and in Canada.

I've turned to Priceline several times now for rental cars, with mixed results. Last year I got a rental car in Columbus, Ohio, saved a few bucks, no problem. A more recent Priceline experience, however, proves that it's always wise to do some research before submitting your Priceline bid.

The goal: A 3-day rental to and from Detroit. Before I submitted my bid, Priceline's site showed that I could get a car from Alamo for $12 a day. So I submitted a bid of $8. No luck. $9. Nada.

What surprised me was that Priceline came back with a counteroffer -- of $13 a day. Huh?

Obviously I ignored the offer, made my way to Alamo's website and rented a car for the weekend for $49 and some change.

The lesson: Priceline has some great deals, but it doesn't have a monopoly on them.