They say the bronze plan has real time scanning at $15 but that'd be odd as you don't get live prices. Silver plan definitely has live scanning and will do you what you want at $25 a month or $250 a year.
I found it pretty versatile when I was playing around with it.
prophet.net as mentioned is good and will do what you want I would say.. its web based and java charts so that is a bit slow but it works.. real time java charts are fine tho for basic stuff.. you can show results of scans as a page full of small charts, which can help for visual scanning of oportunities..
stockwatch is good except for the fact that you have to add the cost of esignal or another feed to its price.. so cannot be called an inexpensive option..