Great response to direct mailers, nothing is cash-flowing!

[Mike Street]

So I've sent out two rounds of direct mail totaling around 1,000 letters. I've got a 1% response rate. I've made 6 offers. All of those offers were below market value and only cash flowed $100 per door (all duplexes) and had a mere 3-4% cash on cash return. I'm using the BiggerPockets calculators. It appears all the duplexes sold on the MLS are not making sense as investments. How do I get these off-market sellers to sell to me when the market is on fire? I'm in New Hampshire on the seacoast. I only market to 2-4 unit properties.