Go to...

http://rawr.codeplex.com/

and download the latest version of rawr. It's a gear comparison tool, that will tell you, based upon your current items, how big of an upgrade certain pieces are for you. You can compare how good each piece you can buy will be for you based on theoretical dps increase, healing throughput, time to oom, pretty much anything , and make your decisions based on that. It's an incredibly useful tool that I highly recommend using to plan gear choices.