First 4-Plex: Deal or No-Deal?

[Marcel Theisen]

Hi,
I'm working on my first investment deal so I would appreciate any advice.
4-Plex: $205K (already negotiated down as much as possible from list price).
Marginal neighborhood- relatively strong rental area but not expecting great appreciation.
3 units are renting at $600 (2B) and one at $800 (3B). Locked into 12 month leases.
Current rents are at market or just slightly below (comps at $625) so possibly $100 more total monthly income if raise rent after first year.
25% Down, 30 yr mortgage @ 4.5%

Monthly:
Rent: $2,600 (Coin-op laundry extra $100/month but I've left this out to be conservative)

Expenses:
$782 P&I
$68   Prop Tax ($810/yr)

$365 Utilities: Water, gas, electric, sewer (average based off past year bills)
$260 Prop Mgmt (10%)
$130 Insurance
$58   Trash (575 year)

Those are my known expense amounts. Tenants pay their gas/electric. Above utilities include owner-paid hot water (and electric from common areas).
I've run the numbers many times using different expense scenarios and figured in 10% vacancy. I've tried the 50% expense rule as well as testing other scenarios estimating higher expenses and major repairs and still come up with positive cash flow but would like to see what other people come up with based on the known amounts above to see if I am off on my calculations.

Thanks,