Two scenarios, both with 20% down conventional financing:
1) Home price $800,000
Principal & Interest Payment @ 3.5% = $2873.89
Principal & Interest Payment @ 4.5% = $3242.79
Monthly difference = $368.90
2) Home price $ 350,000
Principal & Interest Payment @ 3.5% = $1257.33
Principal & Interest Payment @ 4.5% = $1418.72
Monthly difference = $161.39
Both calculate out to just under a 9% increase in your monthly payment. This may help you regardless of your home purchase price.
There are plenty of mortgage calculators on-line you can find,
I just wanted to make it pretty simple for you to see what the difference will do.