Just make your own caller with a pa speaker and mini 9v amp from radio shack, there is a website call varmitals.com i belive, he has intructions with pictures its very easy, it wont be cordless but you can get 50ft mono speaker cables for 5$ on amazon, then just dowbload calls from westernrivers.com or his page they are free. youll be at under 50$ asuming you have a mp3. I used this exact set up for 2 years and it works well plus your not limited to any memory there are tons of free sound files out there. Good luck!
Got a Johnny Stewart 612 Deluxe for sale in classified. I'm around York and would be willing to work out a good deal for ya. It's a good call for someone who's just getting into it or doesn't wanna spend a lot!