I use Oanda, and use the esignal forex charting service (perhaps the best data feed as it is from GTIS). Not "cheap" - but often you can see price moves a second or two before they show up on Oanda (who I use). (don't try and arb Oanda as they can kick you off for doing so.)
Optionscoach, Tradestation is not cheap - I'm looking at their spreads and they are way high (3 on euro/yen, 4 on aussie, swissy - versus 1.5 on euro, 2 on aussie, yen and 3 on swissy). Better to pay for a charting service with the spread that you will save over the long run if you plan to do any decent kinds of volume. If you plan on scalping 10-30 % of the daily range you need to have access to the same spreads that the institutions are paying = Oanda or IB.