I was at an ACE Hardware store in Medford Oregon and found a large selections of springs. I also have an industrial hardware store near me that I use.
I haven't checked a place like Lowes or Home Depot, but they might.
I would think that most auto parts stores should carry a spring selection (albeit they might be smaller springs).
Why not a safety cable from bulkhead to bonnet that can be unlatched after poppin ghte bonnet? At least the thing won't flip on you...
I thnk the straps are the way to go - they look great too.
Mike