I'm not going to debate the merits of more expensive capacitors or resistors with you. Feel free to spend what you like. It's your project. But be aware that many DIY builders have made serious efforts to determine if "high end" capacitors or resistors make an audible difference. They clearly showed that no one could tell the difference between inexpensive or high end caps and resistors as long as their electronic values were the correct ones.
Good luck with your build. The cabinet may be complex, but according to jinjuku, it's worth it.