I have taken a fair amount into account on my math for this as far as I'm aware.

Our current rent is $1850 a month, including utilities.

On a $450,000 house, we would have at least $90,000 available for downpayment.

With closing costs rolled into the mortgage, and a 4% mortgage rate, the mortgage payment would be $1,737 a month, based on 30 year mortgage payment equations I found a while back and rolled into my spreadsheet.

Including the homeowner's insurance (minus what we currently pay in renter's insurance), plus a monthly payment for the property tax, yields a monthly payment of $2,183.

Since the paying of property taxes starts making it worthwhile for us to itemize on our taxes, that's when that information comes into play in the math.

I total up the interest, property tax, and state income taxes, and subtract the standard deduction from that total (because that's the actual value of itemizing over the standard deduction for me). I then calculate what my federal taxes paid on the original AGI would be vs the new adjust AGI with the deductions. That is split into a monthly value and the savings is accounted for in the total costs of owning a house per month math. That gives me $1911 a month.

Then, finally, I assume $120 for utilities and $100 for maintenance that I'm not currently paying. From our experience living in a house in the area before now that number for utilities doesn't seem out of line for us. So, that brings the number to $2,131.

(Fun enough, my equations in my spreadsheet are rolled up for a whole range of home prices and can have multiple factors changed quickly to make alterations - helpful as hell.)

It's entirely possible that my numbers for maintenance will be higher, but $100 a month seems reasonable overall.

According to the nice website

http://www.amortization-calc.com/, it seems that in the first year I'd accrue $7,300 in principal. My payments for home ownership (split into a monthly value) would be $281 in comparison to renting ($3,372). The increase in value of the home if a 1% increase happened (not saying I'm planning on it, just a for example) would be $4,500. And of course, if I just had the money in my funds, assume a loss from not investing of $6,300. So, if I added and subtracted those, $7,300 + $4,500 - $3,372 - $6,300 = +$2128.

Now, I'm not saying that I'm planning on buying a house for the sake of making myself wealthy, but I'm a planner, and being able to plot out these changes is helpful for me. If prices go up or down I don't care so much as I've plotted out what to generally expect in a reasonable way. For instance, should I assume that maintenance number to be $200 a month instead? I'm much more likely to try to work on something myself (within reason as my skills grow) when able.