If you do FHA and only put 3.5% down total payment is 1256.
Both of these are 30 year fixed.
Hope this helps.
This is really pretty simple stuff. Here's one of the many mortgage calculators available on-line that give you a good rough estimate:
Assuming that you have good credit, $100K of mortgage runs around $600 per month. That is just Principle and Interest - the loan itself. Just extrapolate that out for the amount of whatever the mortgage is on your home.
Home Insurance is pretty reasonable - on a property like that, it's likely in the $500/year range (not counting perhaps earthquake insurance - we "have that" here - but it's free since we don't get them).
BUT - then you have Mortgage Insurance - if you don't put down 20%. This is perhaps $75/month for that property. Taxes will also be factored in to your mortgage payment - held in escrow by them and they pay them for you. So take the yearly takes - say $2400? And add another $200 each month.
Technically, you can pay your own taxes directly if you put down 20% BUT the lender will then charge you a slightly higher rate. On a property of that cost - it's usually better to take the lower rate, and let your lender collect the taxes and pay them for you.
Ah ... and then there are association fees. These can really affect your real monthly costs. Some of these are very reasonable, like $50/month or $150 per quarter. Some are very expensive like $250/month. So be very careful about association fees - they can sometimes ruin the entire economic model for buying one place vs. another. Generally (not always) townhouses have much more reasonable association fees - but that's more true here in my market and may have nothing at all to do with yours.
Note: we haven't discussed closing costs at all - when you buy they will be part of the equation too.
I hope this helps!