I am always on the search for cheap hackable devices for robots. I have found a couple here you can use to add cheap, easy, and unlimited speech to your robot.
SMACK TALK for X-Box 360 Promo for "SAW III"
Both of these items sell for under $10.00 and can easily add decent quality speech to your robot. The promo unit for "SAW III" will record and play back up to 30 seconds of continous speech. It has a 1" speaker, built-in microphone, and runs on 2 AAA cells. My Grandkids have played with it for weeks and have not broken it or run down the batteries. You hold down the record button for as long as you want, (up to 30 seconds), and when you're done, press the playback button and hear what you've recorded.
The SMACK TALK records 5 different addressable phrases, (up to 5 seconds each). It runs on 3 AAA cells, has line-level and microphone input, (no built-in mic or speaker), and provides mic level output. Both units will retain the recordings in memory without power.
Both circuit boards are very compact at about 1.5" square. My first mod is to do away with the batteries and run them off a 5 volt regulator. They can be easily mounted with standoffs using existing holes. The second mod is to get the audio to interface with a standard audio amp like an LM380. And of course the next mod is to provide an interface to replace the "button press" commands with something more suitable to logic level switching so they can be operated by an MCU or even simple bumper switches, (excuse me), (out of my way human), (low battery, must find charger), etc. I'm thinking the easiest way to go at this point is a quad analog switch IC like a 4066 or equivelent.
My ultimate goal is to take a plugboard, (Vectorboard), and mount about 4 of the SMACK TALKS, and 1 SAW III on it along with the 4066's, and a suitable audio amp IC, a 5 volt regulator, and run all the lines to the edge connector so it will easily interface to the card cage in my bots. This way also, I can move the card to whichever bot I'm taking out and not have to build multiple speech modules. You could also customize your bot by downloading speech clips from your favorite character. There is always the speech synthesizer built into Windows if you prefer that 80's WAR GAMES feel.
I will updating this blog with more pictures and schematics when I return from vacation.