mp, your deck sounds delicious, I'll CAT you for some photies if I may. It's very interesting how our two designs / styles / approaches sound so very different, but I bet both decks look great.
I disagree, though, on the price issue. Yes, hardwood is more expensive - but it's not that much if you shop around and have a haggle.
For example, Merton Timber have regular 20 X 95mm softwood, pre-treated boards for £99 / 100 m here
Similar in hardwood balau costs £155 for 100 linear metres here
Yes, that's a 50% loading, but on a project of, say a 4m X 4m deck, that only shifts the deck-board cost from approx £176 to £264 - I think the extra cost is repaid in improved 'look when wet', screw / nail grip, durability and lack of movement. Of course, joist / post costs remain the same. Either way, if you get involved in the design / work yourself, you will save an absolute fortune.
(calculated at 11 linear metres of board to make 1sqm of deck).
OK, here is my magic link of the day: Hardwood decking at WHOLESALE prices for your project from Timber Connection . I have never used them myself, but their balau is just £85 per 100 m !!!
Interestingly, if you try and get a 'pre-pack' kit, you pay more:
B&Q do a 2 X 2m kit - £258 . That's £45 / msq excluding any deck treatment products.
Like you, mp, we also had quotes and they were insane. If individuals don't have the tools / skills / time / confidence to do this, I wouldn't hesitate in recommending a professional chippy - or carpenter, tassis to do the job for you.
PS - ref wastage - if you're very clever and calculate well, you needn't lose much more wood with cuts 'on the angle' as once you've chopped to create an angle, the resulting off-cut can be used as the next piece along with the same cut angle already done !!!
I concede they do take longer and are a bugger to cut. But I wasn't the one cutting it !