Gun shop, gun show
Walmart
Gun shop, gun shows, e-gunparts.com
I beleive AirsoftMegastore recently got them in stock.
I have an AA Arms AP9 in very condition, original owner, bought new in 1988, I'll give it to you if you buy the three 30 rd and one 20 rd mag for $300 ;-)Ill buy it with all the clips or just the clips either way
The Kimel firearms company is out of business, so your best bet is online. Either gunbroker.com or try Numrich Arms.
Where can I purchase a magazine for a American arms P-98 . .22 cal. I think they are 8 rounds. Clone of a P-38.
Try e-gunparts.com
Which model? If it is the t9 or t8 pistol then you have to buy an adapter for a 20 oz tank.
Contact the maker, want ads, gun shows, gun shops, internet auctions.
In the US, you need to locate a dealer in your home state that has a special license ( commonly called a Class III) to sell suppressors. You will need to apply to the BATFE for transfer of the suppressor to you, and pay a $200 tax on the transfer.
You might try a search on Commemorative Arms Co. Supposedly they purchased a supply of repair parts for the Nomad, Challenger, and Medalist