Marketing expenses & yellow letters response rate

[Account Closed]

Hi, 

I'm new to wholesaling and I was wondering what is a normal response rate from Yellow letters and bandit signs. 

So far I've spend a bit over 1,200 on yellow letters (first mail campaign) and I haven't close a deal yet. I feel the response rate from my campaign was extremely low. I received about 20 calls, however, only 3 people where motivated. From those 3 people, none of them could sell me the house because ther need for repairs was substantial (not enough equity for an investor after wholesaling the deal). I'm targeting people on  pre- foreclosure stages, probates, and absentee owners. 

I've also put up bandit signs which I received calls but only from unmotivated sellers. I was wondering if you guys use any site in particular to get your leads? So far I've been using list source for absentee owners and ILFLS.com (I live in chicago) for pre-foreclosures and probates.

I understand it takes times and effort, but I feel 2,000 on marketing expenses without closing a deal might be too high. Perhaps I'm not getting the most updated information for my leads. Any suggestions?