PC on greens.

How much is Brohn's Staff, Brohn's Holy Rod, The Stonehart, and Drago's Flatbow worth in total?

try taking a look around before you post...

Green Item Baseline Pricing
http://guildwarsguru.com/forum/showthread.php?t=66631

you do the math...

Sorry, last time I saw a post about greens, I found out that the prices were very different. Just wanted to check the current price.

Prices are updated with the help of reputable traders; of course they're not updated every single day, but they're quite accurate. The thing is you can really find people selling the same item with a wide price range, so take the guideline prices as an average/maximum value.
For popular items such as Rago's or Bortak's or Drago's you can ask a little more, and for other items you will have some troubles asking the guideline prices.
Still they're a good headline for what to ask.