While playing around with some cheapo external speakers on my Propeller BOE at Parallax, Andy alerted me to one that Kwabena had last summer as an intern. I contacted Kwabena and found out it was the Veho 360, a really audible speaker with a short cord and jack, slider-adjustable volume, and USB recharging. Purchased two of them. They're $16 each on Amazon http://www.amazon.com/Veho-VSS-001-3.../dp/B002CS2T4I and probably cheaper elsewhere. Ask erco to find the best deal.
These are of great quality. Plenty of volume and responsive to different frequencies. They'll fit under the Propeller BOE on a PropBot and would be considered an absolute must-have for anybody who picks up a Propeller BOE when they are released (update: just after Christmas, and yes, I'm doing everything I can to get this production underway). Having seen some of the examples being developed by Andy and the education team I think you'll want one of these. Below is an example with my primary use at the moment, a talking ultrasonic distance sensor.
The speaker is louder than it sounds considering it's on level 2 (of 3) and that I'm talking directly into the camera's microphone.
From my home office, and only reporting erco-worthy news finds. . . Ken Gracey