According to people who've looked beyond the headlines, that £3.7 billion includes most, but not all, of the money (about £2 billion) already spent or committed for design, long-lead items (not necessarily for just three ships), & new facilities built for long-term support. It's not the manufacturing cost of three ships.Actually that is pretty much in line with what Australia has budgeted for its new frigates. Australia is looking at $35 billion for 9 frigates and the Australia and Canadian dollar is fairly equal these days.
The UK is paying around £3.7 billion ($6 billion) for 3 type 26. That is about half the price but I am not sure what that includes.
I am told that they will be recycling a lot of the equipment from the type 23 so that would keep the costs down.
Type 26 - where does all the money go?
I've read reports that because of building & refit schedules it won't be possible to do a one-to-one switch of kit from retiring Type 23s to Type 26/31e, & we're likely to need a couple of extra ship sets of CAMM launchers, radars, etc. I think that the first to be built would probably get new kit, with following ships getting the (presumably refurbished) equipment from the T23s the first few new frigates replace.
The trouble with all this contractual & budgetary jiggery-pokery is that we can't tell how much we're paying for the ships themselves. It still seems a lot, though.