These are all good things to consider.
My philosophy is "fast nickles are better than slow quarters". Which means if you pick something that is easy and cheap for you to make, it will also mean it's cheaper for the buyer. The economy is so scary now, even 9 years after you posted this, that people can't afford much.
You also might think of things that are flat. I know that sounds weird but if you can slip your craft into a padded envelope and send it for less, people will buy more. I hope those two tips helped.