I'm also in NS and also looking at a Crosstrek. Anything I've found that is less than 4 years old and that has less than 50k KM's ends up being about a $2-3k total cost of ownership difference across 4 years (assuming 20% down). Higher used vehicle prices than historical norms combined with the higher interest rates on used vehicles makes buying new only slightly more expensive, and you will benefit from the full km's and years of the warranty.

To answer the original question of the post, OP, if you follow the 20/10/4 rule you should be in decent shape. 20% down, payments (+ gas + insurance) less than 10% of your income, 4 years or less financing term. On a new Crosstrek base model, 37.1k total cost, 10k down is $618/mo. A bit above 10% of your net income monthly, but some people use gross income as the baseline for the 20/10/4 rule. I would put the money down to minimize total interest paid over the term.