It seems to me that with $100 put aside for ESO that would get you the game and about 3 months playing time. During that 3 months you could be saving money to buy another three months.
Lets take into account that the game is probably a minimum of 6 months away from being released. How much more could you tack on to to that $100 in that time? Saving just $7.50 cents a month gets you another 3 months playing time.
So, I think you probably could afford to play the game for many months so let's just state the true fact here, it is that you just don't want to pay the subscription fee, That is fine. There are plenty of things that I would like to have that I make a choice not to buy because of money issues. We all have to make those choices. It looks like you made the decision not to play ESO. Personally I would be thinking of ways I could save a measly $3.75 a week? One less trip to Starbucks. A few less trips to the vending machine. Shoot I can save almost that much simply by tossing my change in the jar at the end of each day.
I would not be blaming ZOS for not checking my budget before setting the price. They have their own budgets to worry about.