Every device I've ever read with (Palm Vx, Kindle 2, Kindle Keyboard, Kindle Fire, Nexus 7) has been the ideal weight.
Instead of worrying about grams/ounces, I'd recommend simply putting a lot of different devices in your hand and seeing how they feel. It's quite possible that you're not all that weight-sensitive (like me). Plenty of time to look up the grams/ounces once you know if it's a factor or not.