Yes, eCrater is a FREE marketplace and online store. When you register with eCRATER you receive a customizable free online store. In addition, all your products get listed in their free online marketplace. Hidden costs? Not that I know of. If you've got more questions, I suggest you try and visit their community (forum). I'm pretty sure you'll find the answers you're looking and probably even more.Link hidden: Login to view
I have not personally used Google Checkout but here are a few links that might help you out:
Fees:Link hidden: Login to view
User testimonials:Link hidden: Login to view
We also have quite a number of members using Google checkout, I hope they can share their experiences with you.