that bat detector sounds like an interesting bit of kit, is there any particular makes or models to buy/avoid as there seems to be a massive variation in prices and models from £30 for a kids toy one upto £250 for a serious bat geek oneMines just a magenta mk4....http://www.nhbs.com/title/156154?title=magenta-bat-4-bat-detector?bkfno=171848&ca_id=1495&gclid=CK6fuoHSns8CFYeVGwodP3ENVgThis is cheapest iv found (usually around £90 on ebay)
Iv had this model for severel years and have no inclenatin to upgrade, it's a great bit of kit! I often lend it out to friends it's had a lot of use a