I was doing a little aviating a few days days ago and flew into a small town airport with cheap gas. (KELA- Eagle Lake Texas) One N-S runway. No taxiway so you have to back taxi on the runway. After I topped off, I taxied to the South end of the runway, preparing to taxi on the runway to the north end to take off. A crop duster took off as I sat just off the South end. He had made no radio call but I saw him. He made a low left turn out. I waited a couple of minutes to see if he was going to come back. He was flying a very low pattern, so went behind trees. I didn't see him, nor hear a radio call, so I began to taxi to the other end of the runway. Then I see the duster coming back, very low, lined up to land as I was taxiing toward him on the runway. I broadcast, AGAIN, that I was on the runway, and I flashed my landing lights. He aborted the landing and flew over me. I got to the end of the runway, pulled into the run up pad, did my run up, and pulled up toward the runway and broadcast that I was departing runway 17. No planes visible. No other radio calls. Just as I was about to turn onto the runway I glanced left one more time and spotted ANOTHER duster on a longish final about 50 feet agl! If I had not been in a low wing aircraft (and not taken one last look) I would never have spotted him. I yielded to him, of course. He landed and turned off the runway. I then, very cautiously, took the runway and got out of there. I realize that many ag planes are not equipped with radios but if they are operating out of a public, municipal airport, the least they could do is carry a hand held to broadcast their intentions even if they aren't listening for other broadcasts. It would also be a good idea for the ASOS to have a Caution remark that there are AG operations at the airport who are NORDO. I placed such a comment in the Foreflight remarks section for this airport. I realize you should always look carefully and be aware of what's around you, but when planes are not flying standard patterns but are basically hedge hopping, AND not communicating, it really ups the pucker factor. I plan to avoid that airport in the future.