So, you want to buy something? You ask your parents, only to be brought down with a NO. Well then, read this guide and it may solve your problems..

[edit] Steps

Choose your product. Don't go overboard like asking for a car, but something like a video game or a CD.
Do a little bit of research. Try to find a good deal on the internet. If this works for you, your parents might not mind ordering a product over the internet.
Make sure you think about it. Think about a good way to ask them like "Hey mom/dad? I want a new video game. Do you think you could loan me ___ and I promise I'll pay you back."
If they say no, you could ask them to think about it for a while, or tell them if you don't pay, they can take whatever you bought and sell it or return it to a store.
Make sure you can get it easily. when your mom/dad asks where it is you don't want to answer with "its across the city" or, if you live in a smaller town, "its at <name of big city nearby>"

[edit] Tips

Don't bother your parents every second of the day with"when can we get?""lets go! Come on!" because then they're sure to say no.
Be sure to pay. if you don't, and you used the "You can take it away from me" line, then you will loose it, and your parents won't loan you any money for a while.
This works best if you parents pay you to do chores or to work with them.
Don't ask to use your allowance if you have one, because then they might say "You don't work for that money so you don't deserve _____"