Depends on the engine and how many tools come with it, as well as if its an open source engine vs a set source (open source needed for porting). Also some engines lease per game, or via royalties. Like you might pay $10k per title or something, vs unlimited use.
To put it into perspective, my dev team wasted a long time trying to build our own engine, and we secured a solid one in closed source form (PC only) for about the same price as a PSP. When we want to port the game, we will have to drop $10k to get the open source version to bring the game to consoles. So if we sell 15 copies of our game at $10 each on the PC total, we will break even on that investment (tho we still would have to recover thousands of dollars already invested for other stuff)
The cheapest engine I know out there is Dark Basic Pro, which is more like a scripting system overlaying a core Direct X/C++ engine. DB Pro can be acquired for like $80 US and be used unlimited. Most of the code could probably port directly to XB360, as its all direct x oriented. The neat thing about engines is that the graphics have next to nothing to do with them. You can have the Unreal 3 engine and the crappiest modelers on earth, or have something super basic and some pro looking models. A talented team can make good stuff with minimal tools.







