If the rule is set up as suggested in the first post, then I think I’d hesitate to buy tech. I’ll wait for somebody else to make all the sacrifice.
There is the advantage in getting to use it straight away. Also, some techs are more useful to some powers.
I agree with Johnmk. Why don’t you just put different price tags on each tech and any country can buy them at any time?
I also think Lozmoid has a good idea with his historically accurate tech. I’ve thought about this before, as well. I think it would be a good idea if the price of each tech depended on which country you have. Example: Radar costs 5 for UK, but 25 for Germany. Heavy bombers cost 25 for USA, but 40 for Italy (normally precluding Italy from ever getting them) To me, this makes more sense than any power being able to copy tech for the same price (original power had to take the chance, wait the time, sink the money in…)