As you say yourself, it's four years away. There could be twenty pubs on the doorstep of the stadium with no guarantee they'll still be running in 4 years.
Cost has risen, but so did the cost of the training ground as the club decided they wanted a hybrid pitch. They've raised the costs of the training in two years. I'm confident they can find teh investment for the stadium, along with a manageable debt which was always the plan.
Running a supporters bus up the road will now be a far more attractive (and cheaper) option too.