Id like to propose if admins decide to make new Tc that it works like this. 

Obviously it would start from Q1, then they decide the price for further upgrades so people can upgrade it how they wants. For example, if someone leaves it at Q4 his daily expense to train would be 0.4. And upgrade is paid only once, that time you upgraded it from Q3 to Q4. 
So daily cost to train would be 0.1,0.2,0.3,0.4 and 0.5 depends which Q is your new Tc.