After all expenses it generates about $270 per month.We tried getting a HELOC but got declined because our primary does not meet the amount required, and we cannot do it for rental properties.

Here's a very interesting article that predicts massive job losses in 2009 will cause housing prices to continue to decline.

Low entry level pricing, things cashflow, population growth, declining income tax until it reaches zero, 11 billion dollars of investment into Kentucky over the past two years.

(was anyone else buying in 2007 and in 2010, prices finally stopped declining and took another 3 to recover to 2007 levels?) 

So I would use some additional more organic methods to verify the rentometer results and conduct some research into whether rents have actually gone down in the area such as by speaking to local PMs, reading local RE industry reports and articles, looking up comparable listings, speaking to as many tenants and RE agents in the area as you can, google, etc. and if some or all of these sources confirm what rentometer says then try to determine what might be causing rents to decline (if indeed they are).

This is because every real estate asset kicking off $100k NOI is not equal and worth the same thing.For example - would buy a Class A multifamily yielding $100k annual NOI in a tier one city or a aging strip center in a declining market also yielding $100k annual NOI?

Detroit and Cleveland for instance have declining populations.

Will it flatline or decline?

There's less competition cap rates are higher but continue to decline which means that values are increasing over time.

Price declines happen there first, since most wealthy property owners are more  aware of coming trends.