I think you may advise your ECA to sale as much as digital products, because digital products have no shipping problem.
Tell them to keep prices within $1 to $5 as this is a affordable range for any one.
Digital products should be Internet base business related. People are mainly searching for advertising scope for duplication.
If people are getting some PSA through ECA's product, then that will be more popular and sale will be high and accordingly ECA's and your income will be high.