i agree with the bmxes generally look good part. they do!
i bought a complete bike about 14 months ago, with parts of all colours and materials. black, orange, silver, grey, polished, blue, red and yellow, alu, steel and carbon fibre.
14 months later, ALL parts have been replaced. I've only replaced things which have broken or have needed replacement. my bike is basically black and silver, with some gold. i replaced the old/broken parts with stuff i knew would work well, and some wild cards. all of the wild cards have been replaced, as they broke eventually, and quicker than the other parts. one of the cheapest parts on my bike is the rear hub. a 15 quid welded deore. the axle is bent, and it doesn't spin very well. but i don't notice it when riding, so it's fine.
i run a hope xc hub on front, and a 10 quid THN headset, which has worked flawlessly for 10 months.
my bike is worth a fair bit, and is specced with mostly "TF-safe" parts... they work though, and the bike looks pretty.