You may find gas spring form car spare part shops.
The problem what I met was that the spare parts was announced by vehicle models etc., not by dimensions.
Mine springs were for tractor doors of old Ursus and Zetor
Here in Finland was very hard to find the fasteners and ordered them from Denmark who sell the gas springs as well (link bellow), but their price for gas springs were quit high.
I think I paid some 20+ ? / pcs from local sapare part store.
The fasteners arrived in 2-3 days from link bellow. On the site, there is also a calculator for spring sizes.
Take care the stroke won't be longer than gas spring does, meaning the max destination from lid hinges no more than the stroke.
Gas springs:
http://www.industrial-springs.com/Good luck
To attach the fasteners I used dome head screws 5x15 with 2,5mm drillings.
Dimensions something like this: