Any camping section will sell them. Walmart will have them in camping, look in the coffee maker section, We bought an all glass model for a project. Great coffee if filtered well.
My great grand mom used a wood cook stove, I watched the coffee maker perk.
good luck

If you will truly be backpacking, you will more than likely find the old style percolators to be heavy and quite bulky. They are certainly available still - as the other answer mentioned, Walmart will likely have them, as do outdoors stores like Cabela's, Bass Pro, REI, etc.

For backpacking, I have a few different means of making coffee, and will switch them around from trip to trip. If a good strong cup of joe is what you're after, there are some great french presses that are great - and if you use the JetBoil stove, there is a java press for that too, which I'm told is excellent. GSI Outdoors manufactures a whole variety of coffee making toys... including the percolators, coffee filter baskets, presses, espresso machines, etc. LOTS to choose from.

http://www.gsio… (Note, there are 3 pages of goods!)

For ultralight backpacking, I hate to say it, but I tend to use Starbucks VIA packets or instant espresso powder... and sometimes I spike either of those with a teaspoon of hot cocoa powder.