The loan interest and loan term has a GREAT effect on how much your mortgage payment would be.
If you do 20 years vs.
your difference would be a lot.
You also need to let us know what your property taxes are,
because the cost of them is usually included in your monthly mortgage payment.
your monthly home insurance should be calculated in.
I used some general assumptions based on mortgage rates and property taxes,
but the amount does not include homeowners insurance (which is usually around about $75/month)
Taking out a 30 year mortgage,
with a $20,000 down payment,
if the interest is 6%,
and your property taxes are around $2400/year then your monthly mortgage payment would be around $880/month.
The difference could drastically change with only a 20 year mortgage (the payments would be much higher)
and the property taxes are probably different than what I calculated.
I would assume safely anywhere from $800-$925 a month based on normal mortgage rates and property taxes.