I can't find any more good deals in my preffered area. What do I do?

[Emanuel Toma]

so I started investing in real estate and bought 2 properties (condos: 1 in 2014, 1 in 2015). They are in a great area and I found them trough direct mailing (I could find no good deal trough agents/online/papers; if a property is on the market it is usually to late to get a good deal in my area). The last property I just finished renovating and rented it out the next day. 

Now I seek some more properties to buy, but I can't find any good deals. I have sent more direct mail (used the same strategy), basically the same letter, but the calls have decreased in 3 months to the point that only about 2-3 people called on my last campaign (previous calls would be 20-30 after campaign). 

The area I prefer to invest in is near a big university, very limited inventory and in high demand for renting (so many investors present). 

I send a general letter to every property in the area. My plan is to keep sending a similar letter to every property every month. But I fear the very low response rate from my last campaign.

What should I do? How can I find good deals in my situation?