There are many places to find working flintlocks......Check in the The Thieves Market section in the Pub under the venders index thread.
If you are looking for used ones there is Gunbrokers.com, auctionarms.com, Gunsamerica.com or in the frontierfolk.net site inder trade goods.
Since you have allready had experiance building a kit try http://www.muzzleloaderbuilderssupply.com/index.html.....they have some really nice kits.
Hope this helps some.
Pegleg