I live in Ireland....
We've got the Euro also. And Euro prices.......
Insurance Companies here now have what they call a 'Minimum Premium' ( set my them, of course.) This might be Euro 280 or Euro 335 or what ever the specific Co. feel like making it! So OP's figures are not achievable here.
Classic car insurance seems to be really cheap in the U.K. going by figures given in some of the classic car mags.
Have you tried an Insurance Broker. Try to find one who specializes in arranging cover on Classic vehicles.
Ask around other classic car owners at car events, gatherings, shows and from club members in your own country/region.
See if there is anything you can offer to do to reduce cost of insurance e.g. mileage restriction, garaging of car, etc.
Maybe it's possible to insure the car for less than a full year?
Or include it on another policy? Some classic car policies allow more than 1 vehicle to be covered, maybe have someone else add your car to their policy and add you as a named driver?
A good Broker should know all the ins-and-outs.
Al.