I don't the upfront costs, but I wasn't expecting the monthly costs for 100mb/100mb to be that expensive. 
I know, I've also been wondering lately about the cost for getting Fibre, paying up to £10k (depending on distance required) for this I can tolerate but I can't then tolerate the stupid costs involved monthly.
If I ever make these plans a reality I'm thinking of contacting Openreach or BT Business and seeing if they would be willing to quote me for the cost of putting in the infrastructure for there native FTTP (Not On Demand Silliness) and then subscribing to BT's normal Infinity 4 service.
However I have very small hope any such thing will happen and hope will be held for FTTPoD2 !