April, I would like to suggest a few things to do that cost little or no money to get your phone to ring.
1. Post creative ads EACH DAY on Craigslist real estate, saying similar things to what your direct mailer said. Vary them up a little. If you are on Facebook or other similar sites, post the ads there too.
2. Also on Craigslist, click on the bold letters that say "for sale". (it's under the housing section on the CL front page.) In the search box, type in "estate sales". Contact everyone that has an ad there. Ask if the real estate is also for sale. Ask the folks selling jewelry, etc.in their ads, if they will let you know if they found across someone selling their house as part of an estate, and offer to call them if you find something that they want. Bird dog for each other.
3. Call everyone on Craigslist that has a house for rent. Ask the person if they would be willing to sell you their house instead of renting it. They may be reluctant landlords and be glad you asked them. if they are not, ask they if they know someone that wants to sell their house. That works more than you might think. Also,call every number on For Rent signs that you drive by.
4. Get some business cards made that say you buy houses. Hand them to several folks each day and get their card. Leave your cards where allowed, such as diners, auto service centers, etc. Get to know people and be genuinely friendly.
5. Ask your mail carrier to bird dog for you and give them several of your cards. They get to know many people along their routes. In fact, ask EVERYONE to bird dog for you. Offer to pay every bird dog $500 if you end up getting a deal on a property that they find.. I have a bird dog contract that I sign with people that promises to pay them, and I offer to do that before they tell me the address. I hope to pay for a lot of them.
6. Target a specific zip code and get to really know very well just what is going on there rather than being all over the place. Drive through the streets on garbage pick up days. See which houses don't have garbage containers out. Those are probably vacant ones. They may be coming up for sale.
7. Call every bandit sign number. Tell them what you are looking for. You might be able to benefit each other.
I can give you many more ideas, and you are welcome to contact me if you wish. You really CAN be successful but it takes more than buying various forms of advertising.