The three that come to mind are eSignal (check Futures magazine for the $79 offer), QCharts, and myTrack. TS Pro (Tradestation6) maybe, if you can talk them into just buying the feed, or if you are willing to open an account.
As you probably know, there are lots more feeds/charting packages, but none that I know of that can be had for less than $100/month outright.