Just as note, with saying "expensive" i don't mean the engine is expensive for it's price, it's just expensive for MYSELF at the moment.
The price is fine for what you get.

Can't tell if they play in the same league. Both are top game engines. I didn't try the graphic aspect of unity3d that much so i can't say something about, i just know what i saw on screenshots and it looks brilliant, nevertheless i saw the same quality with torque.

As programmer i prefer torque a bit more, cause the scripting language is more powerful. Still, i also like the Unity scripting.

Torque can port games to xbox, mac, windows and wii. Unity can port it to iPhone, webbrowser, windows, mac, whatever.

I don't think it's quite possible to compare both engines with each others, they have pros and cons, it always depends on your projects and audience.

All i can say, Unity is worse every cent, you won't regret it. But buying a mac just to get unity.. i dunno, maybe people should get something else then (if they didn't plan to get a mac anyway, since they are awesome :))