What I keep finding out is that my target price is always at least 20% below seller's asking price.Here are my rules/metrics:total economic loss after property is stable is 12% (15% in lower quality areas)incremental rent growth after the property is stable is 2%expenses grow by 2%/yearproperty tax is 90% of the purchase price multiplied by a local tax rate (usually doubles tax from whatever seller pays)payroll $1000-1200/unit regardless of the property size (brokers claim that 30-units don't need payroll but I don't believe them :-) )reserves of $300/unit counted in expensesexit cap rate is 100 basis points higher than current cap rate (e.g. exit at 8% if current cap rate is 7%)cash-on-cash ROI 10%+ starting in the second year; first year may be lower if this is a value-add5 years total ROI (assuming sale) is at least 100%IRR 15%+ over 5 years (al ROIs are net to investors after 20% sponsor override)I can adjust may metrics to some degree but in order for me to get to the seller's acceptable price I have to adjust most or all of them to unsustainable levels.So, what should I do other than keep underwriting and waiting until the market turns down and all of a sudden my numbers would make sense for a seller?

Multiply the two.Utilities-Totally variable, depends on the type of utilities to each property, the size of the property, and the degree of insulation. 

My insight is to run your numbers very carefully, multiply your anticipated annual expenses by 1.5, and don't forget capex.

I manually set holidays and special events in outswitch and apply a multiplier to the base rental rate for that period of time.Outswitch can connect to multiple booking channels but HomeAway/VRBO connection can only be done through RentalsUnited, a booking channel aggregator that I'm currently demo'ing but don't have enough experience to comment on yet. 

Units: 36Building Size: 28,000 SFPrice/Unit: $27,777.78Property Type: MultifamilyProperty Sub-type: Garden/Low-RiseProperty Use Type: InvestmentCap Rate: 11%Gross Rent Multiplier: 5.26Occupancy: 92%No.

Basically, multiply the rental rate by 50 and determine what a reasonable purchase price for that type of rental property should be. 

Asking Price: $695kGross Rent: $54645Gross Multiplier: 13.30 (According to MLS)CAP: 5.1%NOI: $36,066 - they didn't factor in vacancy or management and I believe the posted utility cost is lowMy Estimated NOI: $25115$25115/ 0.051=  $492,500Is it unreasonable to offer $492k - $520k?

Multiply that by 5+ houses (not units) thats 250k+ at a time coming in an out of our accounts.

Multiply this by 100 and it gets an 8 cap.

@David StoneThen multiply your investment loans by 2% and that should be all that's needed.