Found this idea on varmint al's.
I already had the 512mb MP3 player and loads of sounds. The amp and Mp3 player give sound like the mini colibro caller.
The speaker is optional,but is an improvement on sound quality and louder.
Radioshack Mini Audio Amplifier 277-1008 ,from amazon £7.99
Looks like they've got the wrong price on this now???
In/Outdoor POWERHORN 4'' x 6'' 50 watts max £19.99
In/Outdoor POWERHORN 4 Leisure