You can try Craigslist, Ebay, and other auctioning websites. You cant get them in normal game stores anymore.
You can buy it at ebay.com. Ebay.com has basically any video game you need.
If you want to buy a Game Boy Advance nowadays, you'll most likely have to look at Ebay.
Buy a Game Shark then the device should allow you to plug in codes.
E reader is a device you can buy its not in the game.
An action replay is not an in-game device. It is an actual piece of hardware that you buy at your local electronics store (not all have it), where you enter codes using that device to hack your game.
Legally, yes. But, who goes by the rules nowadays? If I look in a dark alley in Phili nowadays, you can find at least 5 people willing to sell to you, below 18, for a high price. Watch where you get them, buddy.
You need to buy a hacking device to texture hack a game.
buy a gameboy advance video cartridge on ebay.
not realy its better to just watch the game show
Its a device you can buy separately, which allows you to use cheats in the game.
There are a few card reader you can buy but they are hard to get nowadays so I would say buy an arduino and do this: http://hackaday.com/2011/03/20/gameboy-rom-backups-using-an-arduino/
Sadly, it's not possible. The only way is to buy a new device to play it on. Your device remembers what your farm is up to.