I'm looking to buy a power supply for my GE Simon 3 alarm system: Part
# 22-129-ITI. This power supply is supposed to allow me to use my X10
lamp module with my alarm system.

Note: I previously did a search, but I cannot reproduce it. I believe
I saw it selling for around $20 in a web store.

For reference, you can find this part # mentioned in this manual:
http://nassausecurity.com/iti/simon3im.pdf

The <a href="http://www.safewatchservice.com/product_info.php/cPath/61_63/products_id/453">60-913
Simon 3 Line Carrier Transformer</a> will work just fine as a
replacement. I believe it's the exact same transformer, but I have not
confirmed that as of yet. I do know it will work.