There is more support for Mastercam than any other Cam package in the world. There are more 3rd party supporters. There's more 3rd party manuals and video training documentation.
But alas... there is not downloadable trial version. Contact your local dealer for a demo and a demo disk.
So here's the thing... every Cam system would have you believe their systems are so intuitive and "even a cave man can use it". Wrong!! Anything with any power at all requires a reasonable amount of instruction to get comfortable. Get yourself some training. It's cheaper to buy some manuals or video training and see how it works, than to buy the software and find out it won't suit your needs. Or attend a class to get familiar with it.
I can tell you from having looked at a number of other systems, that Mastercam has the most features. Features that in other systems they might tell you "Oh... You can write a macro to do that..." Mastercam already does it.
As for the cost... any where from $3000 and up. depending on the type of work you do. Take some advise on that also. Get What You Need. Some people will call their dealer and say "I "Need" 3D mill, Lathe, 5 axis, etc... " and then when they get a quote for $18,000 they'll say "wow Mastercam is expensive". Well it is when you buy all the options you dont need. Remember Mastercam is fully upgradable. Get what you need now to start making money and then get an upgrade to better capabilities when you need those.
Hope That Helps,