No Turntables Just A Microphone

I recently started looking into getting a turntable just to play records for fun. The more I dived into it the more I thought how sweet it would be to get 2 and try out DJing. One turntable alone will put me out $399, so x2 would be $798. So I figure I can start with one and see how I like it and add on from there. My cousin asked me why DJs usually have 2. I told him so that they can transition between songs. If you had one turntable and had to stop and find the new track, party goers wouldn't be too happy. My cousin then thought of the brilliant idea of what to do during song transitions with one turnable.