I recommend using Widget Logic. This plugin is available, free, at Wordpress.org. It is one of the must-have plugins.
You use it in coordination with Conditional Tags. With them, you can place a widget in a sidebar, but tell it to only appear on pages or in categories or even in a specific page, post, category, etc. That way you can use the sidebars you have in almost limitless fashion. You may end up with 100 widgets in a sidebar, but have only three or four appear in any particular place.
It's really rather easy to use, once you get the hang of it, and that won't take long.