Any bookstore either in China or overseas. Even airport bookstores usually have a stock of them. If in Beijing already, ask at hotel receptions. They sometimes have a free tourist type map. Getting a hard copy map should be very easy to achieve. But, of course, if by some miracle you cannot get hold of one, there's always Google maps. As for getting there, you could try being adventurous and taking public transport. There are buses that go to many of the common GW locations. The worst option is organized travel groups. They are overpriced and more interested in getting you to the overpriced tourist souvenir shops through whom they pick up extra commission. Best to try and get there alone or with a group of friends.

1)Buy a pen.

2)Look for  a wall.

3)Write "Great Wall" on the wall you find with your new pen.

4)Visit it now

if your already in beijing, try going to the 'silk market', Sanlitun.. there're lots of buses n hire cars that go daily to the great wall.. or go to your embassy, am sure they'll be able to help you.. and good luck.. great wall is more than the eye can see, hope you enjoy..

You can download a PDF version from http://english.visitbeijing.com.cn/upload/enmap.pdf

If you travel to Beijing, be sure to climb the Great Wall. There is a saying in China that you won't become a hero untill you climb up the Great Wall. There are about eight sections of the Great Wall around Beijing. So choosing your favorite section is very important.

The Badaling Great Wall and the Juyongguan Great Wall are both located to the northwest of Beijing. They are usually coupled with the visit to the Ming Tombs when you choose one of these two sections of the Great Wall. The Badaling Great Wall is very developed and equipped with cable cars while the Juyongguan has no such facilities and you have to climb up the wall by foot. The Juyongguan Great Wall is less commercial with an easy accessible parking area. Its parking lot is very close to the starting point of the Great Wall.

The Mutianyu Great Wall is located in Huairou District in the north of Beijing. This section of the Greta Wall is a little bit less crowded. You can use the cable car to get to the top of the Great Wall. The Mutianyu Great Wall is very green with dense trees.

For More: http://english.visitbeijing.com.cn/thingstodo/routes-strategy/independent-travel/waking-bybike/n214946947.shtml

If you have the time (2 days) www.greatwallfresh.com is always a treat. You will probably have to stay overnight but the younger son speaks good English.