One bulb buyback program is offered by Interlight.
http://www.interlight.biz/
INTERLIGHTS BULB BUYBACK PROGRAM
CALL INTERLIGHT AND ASK US ABOUT OUR BULB BUYBACK PROGRAM. WE WILL BUY
YOUR UNUSED LIGHT BULBS.
Download Interlights Bulb Buyback quote form and mail or fax it in
today!
Quote form is at this site
http://www.interlight.biz/CatalogPDFs/Interlight/surplus%20mailer%20v3
I used this buyback program a few years ago. I chose credit rather than
cash back and was able to purchase a few bulbs that I needed. The quote
form explains the details.
You can do a google search for AV lamp substitution and find websites
that offer this info, such as this one: