As @bobh says, an old iOS device running a custom app would work as a test BLE peripheral. And I bought an iPod Touch for just that purpose.
Unfortunately Android has only introduced native BLE support as of 4.3 and won't yet work in "peripheral" mode.
There are cheaper alternatives too. There are many BLE dev kits out there: https://developer.bluetooth.org/DevelopmentResources/DevelopmentPlatforms/Pages/Development-Platforms.aspx
If you don't want to mess around with wires and breadboards then you could try BlueGiga's programmable BLE USB dongle. It's about 26 bucks and they have example code for the Heart Rate Profile so your life would be very easy: http://www.bluegiga.com/en-US/products/bluetooth-4.0-modules/bled112-bluetooth-smart-dongle/