Well first you have to think about your lifestyle and how it would go with the dog.
~ Many people fail to realize that GSs need a lot of exercise, and need a pretty big area to play in, or to just 'claim' its territory. German Shepherds are very energized and need about as much exercise it can get. Try to walk it about 2-3 times a day on a regular schedule if you don't have a yard, or if you don't want the dog to ruin your yard. It also helps to have toys around the house because if you are not at the house most of the day, it will need something to do when you aren't there. Also, if you live in an apartment I wouldn't recommend this dog either.
~ The German Shepherd also eats and sheds fairly often. If the exercise wasn't enough, food costs and the shedding is also something you have to consider. It's your choice to feed your dog whatever dog food you want, but whatever brand it is you have to make sure it gives all of the nutrition and vitamins it needs to be healthy. Shedding can be the biggest problem for some people. German Shepherds have a black outer coat and a white undercoat so depending on your carpet, it should be fairly noticeable. Since it only sheds a lot when wet, you should see white clumps of fur sticking out. If you don't want the fur all on your rug, just simply buy a brush for him/her. It's simple but some people just can't use $6 on a dog brush.
~ Other than those important questions you have to think about, NOW consider what the dog looks like and its health. Simply check its eyes to see if they're cloudy, make sure it has its vaccinations and you cannot see its ribs. Now it's your choice. If you can afford it, you should take him/her. If you can't, help try to find someone that will take it. You can't let that beautiful dog sit inside a kennel until either some one adopts it or it's euthanized.
~ By description, if you meet the criteria you should definately keep this dog. And you're lucky this dog is only $450, my baby was around $900! But that was probably because he is a purebred...anyways, good luck with the dog and provide it the best of care!
Sorry for the long post!