ahhh well if that's an option and you're not committed to Avis, then absolutely book with the cheapest! As long as you don't pre-pay, then there are no no-show or cancellation fees. Also, don't just book and forget about it--book it, then check again once or twice a week. Rental car prices fluctuate so much. I almost always rebook at least once because prices drop. And, usually, the closer to your trip you get, the lower the price gets.