I would start my search at E-gun parts.com(Numrich Gun Parts Corp.).
Gun Parts Corp www.gunpartscorp.com
Try e-gunparts.com
ableammo.com has them for $13
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http://www.sellmystuff.com.au is the best place to buy and sell items.
Factory magazine for Marlin 80 DL $18 + $7 shipping at ammoclip.com
They don't have clips. They have magazines. You can order them through Numrich.
http://www.e-gunparts.com http://www.brownells.com 2 good sites
Try Numrich Gun Parts Corp.
you may wish to look at larger gun stores in your area for a used model 1892,or you can find some on gunbroker.com,or guns america.
You can get them from Marlin....
Possibilities... www.Factorysound.com or www.Jaycar.com hope that has been a help...