Unity3d is a tiny fraction of the cost of any competing engine. Unreal Engine / Farcry start out costing hundreds of thousands of dollars and some studios might even be paying 1m+ for their licenses.

At $1500 a developer (or $4500 if you need iOS + Android licenses), Unity3d is a steal. Plus you can happily develop with the free version until your company is making 6 figures in revs. The free version is lacking some features but until you get really serious about Unity you don't really need it.