I should have described my rent-buying calculation. I downloaded a spreadsheet template from Microsoft’s website, here is the detail:

Home Rent or Buy Analysis

Initial Assumption

After-tax rate of return on investments 5.00% (CD rate)
Marginal tax rate 35.50%
Estimated annual appreciation of home 0.00%
Down payment on home $140,000 (20% downpayment)
Estimated closing costs $5,000
Estimated purchase price of home $730,000
Monthly rent $2,800

Cost of Renting
Annual rent $33,600

Renter’s annual insurance premium
Total annual cost of renting $33,600

Cost of Buying
Mortgage loan amount $590,000
Annual interest rate 5.750%
Term of mortgage (years) 30
Monthly mortgage payment $3,443
Annual mortgage payment $41,317
Property taxes 12906 (=1.75% * loan * 1.25%)
Homeowner’s insurance $2,000
Maintenance $1,200
Opportunity cost of buying $7,250
Total cost of buying $64,673
Less Adjustments:
Principal reduction in mortgage $7,392
Tax savings of interest deductions $12,043
Tax savings of property tax $4,582
Total adjustments $24,017
Annual after-tax cost of home ownership $40,656
Less:
Estimated annual appreciation in value of home $0
Net annual cost of home ownership

Rent-Buying different is $40,656 – $33,600 = $7K

As first time buyers, I may have missed something, but I looked the formula behind the calculation and they seem reasonable. I really hope someone can correct some errors so the buying won’t look so reasonable/attractive so that I can convince my wife not to buy right now.
I’m so glad and thankful to see so many insightful comments, and I’ll tell my wife to read the forum and hopefully bring reasonable doubts to her.