custom made frames

Generally starting at £1500 and 3 months wait time, some en vogue builders over a years wait. Once-in-a-lifetime purchase for most I imagine.

If it's to replace a second car, a few years tax & insurance justifies it

Well with a username like that, I daresay you have a custom frame - I've heard Viner's are awesome.

As someone that is currently finding out more about geometry than any sane person should have to in order to resolve some fit issues, I can see the appeal. Currently, the Trek Madone looks to be the best fit for me, but if I'm honest, I'm not a fan of the Trek brand. Great bikes I'm sure, but I'd rather have a Cervelo or something, so there's a question of whether I can find the same position on something else without loads of headset spacers etc.

Thus, if you've got the cash spare to buy something that is the best of both worlds, go for it.

I have a very high-end carbon fibre race bike from Ridley which is a thing of speed and beauty...

And I have a custom-built steel frame bike from Roberts which cost a fifth of the price but is like putting on a glove.

I hope I would never have to choose, but if someone said I could only have one bike for the rest of my life, it would be the steel.

There are loads of small frame builders doing amazing stuff in steel at the moment, if you want something that will last and you will lust after for years to come. My two favorite builders (wish I could afford one of them) are
http://www.demonframeworks.com/frames-2/
http://www.paulusquiros.net/

One day

I'd love one. One day.......

I've a Paulus Quiros - absoelutly love it, best bike I've ever had.

And the first ride, it's like getting on a bike you've had years - it's just right, it just fits.

(the silver blue fillet brazed on on their site is mine)