Just remember that with things like rims and even disc brakes, you can easily remove them and use them when you want a new bike. So the cost you spend on parts like that isn't 'just for that bike', you can use it on probably any bike you get. Or atleast as backups.
Just remember to save your old parts, so if you want to sell it you can put the orginal stuff back.
I really think any of those options sound good, it depends on the money you have.