I am not sure where you are located, but I would believe that if there is a store that carries kit cars you should see if they might carry parts for your car. I found a few sites online such as bodykits dot com and yourhotcar dot com.
There is not official store where you can custom make a pillow pet. The only way to customize them is to make them from home.
You may have to find someone that can custom make that kind of bridle. You can start at your local tack store, they usually know of someone that makes custom tack.
I'm just going to assume that you're talking about the custom stage parts in brawl. To get one of the three sets of extra custom items, play on custom stages in 15 COMPLETE brawls. To get another, make 5 custom stages. To get the final add on, make 10 (maybe 15 or 20) custom stages.
I will not tell you losers
Carpeted floor mats are an excellent way to make your car look new. They come in a variety of colors and sizes and can be purchased at your local auto parts store.
Go to the nearest parts store tell them make model and year and engine size and they can tell you. Parts store such as napa, carquest, autozone. 5w30, unless it is the 3.8L v-6 then its 10w30
To design a custom pen you with a logo or motto you can contact Staples promotional products in store to make the pens. You can find custom pens online at Custom Ink.
Custom stationary will make your resume stand out. Try using Microsoft Word, as it allows you to add custom elements to your page. This will look more professional than pictures on stationary bought from a retail store.
Do a search on a cosplay store or ask someone to make it custom.
If you go onto Google and search "Xbox 360 Mods" then you will find sites that sell either fully moded 360's, custom 360's or parts for you to do-it-yourself.
Buy a BMX frameset and put your own selection of components on it.Switch parts out for rarer, more expensive parts, have it repainted.
you cant make a complete custon style, but you can alter the colours. Or you can buy them from the sim store part :)