Do you have a local Radio Shack nearby? You can also find them in door buzzers and smoke alarms.
Hope this helps,
RS, were I get mine, usually around $1-$3 cheap
Dollar tree! I learned about this here! They sell "intruder alarms"that have a piezo element inside for $1., Tear it open and take out the piezo, wire to a jack and you are in business.
Of course Gitty has great deals on them too, but if you just need a couple the shipping may be prohibitive.
I bought one today at Radio Shack for about $3.50. Not all RS stores stock these types of parts. But if you call or ask they can tell you which stores have them.
CB Gitty sell them very cheaply, and they are good quality. You just have to wait for them in the mail.
Tim, Maplin does them in the UK for less than a Euro each. I know that you can't exactly walk to the store, but their shipping to Holland should be quite cheap. Otherwise, if it's just plain piezo disc transducers that you want, I can grab a couple the next time I'm in town and post them to you.
My links don't always work but its:
There's a Maplin in Cambridge - I'm about half an hour away from there.
Sorry, I thought you meant Tennesse USA. No Gitty does not have a store, yet but just give him time and he may be in malls all across the USA.