I've got 10 PR4 com sites(myspace), if you wanna buy links
However I think $200 is just the right price, offcourse on the end all depends from number of sites if your link will be even included site-wide!
i say try it for a couple months. There is definantely extra weight on .edus and .govs. But its pretty hard to get .gov links. So even if they discount .edu's because of all of the spam, they might not do the same to .govs.
If its in your budget, do it for 3 months and see if there's a difference.