Just to add, Burls which do a custom ti for around the £1250 for frame and forks.
Cielo Rosso,who used to advertise for about £700 for a custom ti.
I know someone who had one done, so if you need more information drop me a line (email in profile) and I will find out more.
Bike for life, its depends on you I guess. I tend to get bored so everything for me is short lived. However friends of mine buy one thing and keep it forever, so for them its usually bike for life.