I think you're getting too complicated...
A pound of U-235 contains as much potential energy as six thousand barrels of oil, 34 million cubic feet of natural gas, or over a thousand tons of coal.
Uranium is going to have to be damned expensive before the other resources get to be a bargain.
Now of course a realistic cost assessment would also deal with peripheral costs, like building plants, dealing with waste (including the effects of burning hydrocarbons) and a lot of other issues.