Just taking a swag at what it might cost to buy and own a $40,000 plane
in the Cherokee class, here is what I came up with. Feedback from those
who are wiser appreciated:

Assumption: $40,000 plane bought with a 15-year 7.5% loan with 20% down.

Startup costs:

Down payment: $8,000
Loan fees: $250 (guessed from googling on aircraft financing)
pre-buy activities: $2,000 (inspections, travel to view planes, etc)
reserve for first annual/squawks: $5,000 (not really an expense but need
to have available in case)

Monthly fixed costs (some are annual costs divided by 12):

Tiedown: $35 (verified with local FBO)
Loan payments: $300 (used online loan calculator)
Insurance: $90 (online quote from AOPA insurance agency, $1M/$100K, 160
hr VFR pilot)
Annual: $75 (assume $900 annuals)

Hourly costs:

Gas: $24 (8gph @$3 per)
Engine reserve: $15 (assume engine has 1000 hours left and an overhaul
will be $15K)
Other reserves: $10