I've used box traps (reasonably priced at Tractor Supply) baited with tuna successfully. 

Such as builders supply stores.

They have specific researchers called "research analyst" that do nothing but put this stuff together.There are commercial data companies that supply the info that charge a bunch of money.The key is if the info Is going over a macro level or a micro market.

The seller's agent will likely have some sort of explanation which gets at the issue, in part.Then adjust your max offer price and submit your aggressive offer.

Before going after demand (investors) you need supply (Properties) to be able to close the deal then and there.

In retrospective I should have been more aggressive about cold calling in the first few months.

These will supply the cash flow needed to sustain your daily lifestyle and any other investing you'd like to pursue.Research, learn, take action.

If it is an older house, those were probably gas supply pipes for gas lights that would have been on the walls. 

I've been around to some so called wholesale suppliers but their prices are still astronomical.However if you have a contact that is a landscaper and can supply and install at a reasonable price, please let me know or have have them call me.

Local bank would be your best bet as they are being aggressive with multi family right now and these loans can be competitive.I primary do lower income areas (think sec 8 and gov't subsidy) so banks need the CRA (Community Reinvestment Act) credits.