Time delay relay
I have not but no reason why not. Start by searching ebay, maybe. There's a lot of BS and "china" to wade through but you can learn a few things and get a few sample part numbers, etc, to get you branched out. I have not bought anything from Mourser Electronics for awhile, but they used to not have a minimum, and were very friendly to small orders. Digikey another
You have to be careful what you order. Some time delays energize the load upon trigger on, and delay to off, others don't energize the load until after the delay upon being triggered. Some cycle, some are one shot, etc.