For shipping, you can use the Flat Rate boxes. Those hold up to 20 pounds for one price. You'd have to go to the post office for the international rates for those.
The One Rate Envelopes hold a certain amount of weight also for something like $4. Again, you can check with post office.
People like to see what the prices are without having to click on different links. I know, I do.
Other than what is already stated, I can't think of anything else.