I doubt there are any free ones, but there are a lot that are rather affordable. If I remember correctly, there is one called Cakewalk SONAR for less than $100 for the full program. FL Studio, the program I use, comes with different "versions", which are packages with differing amounts of plugins and such things. The most expensive one is about $300, but I don't know whether you consider that expensive or affordable. Avid Pro Tools, which is what is (as far as I know) used by most professional producers, has widely varying costs depending on what you happen to order it with. The package that I have cost $179 and it came with a small adaptor box thing. It really depends on what you want. If you want more electronic music or don't have the money for recording equipment, I would recommend FL Studio, as it doesn't require any recording to make music. If you want to record things and are willing to dish out the cash for equipment, I would recommend Pro Tools as it is (again, as far as I know) the standard software used by professional producers.