I think a few good points made here.. and while it is easy to replicate, the original requires a lot more resource.
Things that are not normally take into when calculating a price:
1. It is a business - it is there to make a profit
2. It requires space (Land)
3. It Requires a workshop
4. It requires a lot of equipment (Premium brands use premium equipment)
5. It requires human capital (labour). (do you want the best products? You gotta get the the gest human capital. Do you want the best human capital, you gotta pay them well)
6. It needs to do R&D to make sure what it is offering is sound (Again, quality of engineering)
7. It needs to meet regulatory requirements
8. It needs to pay to have regulatory approval
9. It has miscellanious overheads (such as computers, programs, cad systems)
10. It needs to return an investment to shareholders
11. It needs to make enough money to continue this process
12. It needs to take bad cash flows into account
13. It needs advertising & Promotions
14. Endorsements (BMW approved, that aint free)
Those are just some overheads, that a man in his backyard does not encounter.