Affording vs. qualifying are two different things. You'd need to personally evaluate your finances, net income, utilities, etc. to determine if you can afford a certain payment.
As far as qualifying, what Jamie said is correct, 45% debt ratio is a common threshold that most lenders have today with conventional financing. FHA financing can approve debt ratios into the 50's, but you could really be stretching your income then.
With the info you laid out, you'd easily be able to qualify for a $500k sales price, and potentially even a $600k sales price. But property taxes usually scale with the property value, so I am not sure what price you were basing the $7k/year property taxes on. I was using a 2% tax rate, meaning a $500k home would have $10k/annual property taxes, as I know they can be pretty high in NJ (even higher than 2% I've found in some areas).
If you had a co-signer that could possibly change things with FHA financing, but with conventional financing and the loan amounts/down payments you would be dealing with (and could no longer qualify for on your own), it wouldn't help (since the occupant borrower has to qualify debt-ratio-wise anyway).