[Closed] custom build on cycle to work?

I've been lusting after a new road-ish bike built up from parts, and have been advised to look into cycle to work.
Now, I think I can convice my employer to do our own implementation of the scheme, so buying a bike would involve just whipping out my company card -- no vouchers, fees, any of that stuff. As I understand it, from the bike shop's perspective it would just be a normal transaction.

And here we have the first question --
Would any of the bike shops on here be willing to sell me a custom "build", for a price which is the sum of all the best bit prices I have found on the web? I expect that each of the parts already has a profit margin built into it, so it should be feasible? It wouldn't even have to be assembled.

Then we have the 1000 pound limit, which would still stand. After having gone online and priced up most of the component bits, the bike I want is considerably more (surprise!). So I'm wondering what to do.

One option is to try and buy an incomplete bike for a grand on the scheme, and then pay for the extra parts myself.
But I guess that for cycle to work, the sale needs to be of a complete bicycle?

The other option is to try and swap out some of the bits in my build spec for cheap ones in order to come in at a grand, and then upgrade over time. Would keep all the cheap bits, of course, so if there are ownership issues it could easily be returned to its original state. But this seems like a bit of a waste...

Is each of the three things I'm talking about above doable/advisable/legal?
I don't really want to be spending time thinking about it if it's a non-starter.