What are you looking for?
A back testing package available as part of your account such as Fidelity offering Wealth-Lab if you do 120 trades a year, or Trade Station (TS) offering its software at half price ($100/month) if you use them as your broker, or something else? In both cases you have to do the work coding up your system. ( I'm not sure how extensive the commodities coverage of either of these brokers is)
It also depends on whether it is an end-of-day (EOD) system or an intraday system. I don't think WL is intraday.
By using Fidelity or TS you use their extensive databases. If you buy a software package or roll your own you'll have to acquire the data on your own. Depending on what you are testing it can get expensive.
Do a search here on ET for backtesting and out-of-sample for loads of info on those subjects.
