My solution is to spend a ton of hours learning draw9patch, and then it won't take hours to make the buttons. I did this myself, and suffered, but draw9patch is a really simple way to do it, and each image (for buttons) takes me no more than 15 seconds. draw9patch images should are great because you really only have to do them once, and they will work with all densities, as they will stretch accordingly. If you have text in your images then you have another problem. This is frowned upon because you lose the ability to translate your application with a simple stings.xml
My solution:
1. Get awesome at draw9patch
2. Don't use image's with text. draw9patch can be used to center the text of a button correctly and this will increase the ability of your app to be used in different languages. Something that can easily boost your download/sales. This is important, because even if you give your app the ability to target one more language (let's say... Spanish) then it really makes that target audience happy.