KartPro is a website which stocks a large range of Go Karting equipment that can be shipped to anywhere in The United States of America. They do not sell Go Karts themselves though.
Online would be your best option. A site called akers-ski.com is a great place to find many skiing equipment and you can find great sales and more when you purchase here. They also have brand names of their equipment for the picky people.
Chances are you can find equipment like that online on Craigslist or ebay. Both sites specialize in equipment like car accessories.
The most economical place to find cheap gym equipment is on eBay or craigslist or any other venue to purchase used equipment.
You should purchase lubricants from the manufacturer of the treadmills themselves as it is the most reliable source. You can also find them at most mall outlets and equipment stores.
When I did a Google search for "go kart repair in Greenville SC" it came up with Northern Tool and Equipment and Dixie Karting
Birdhouse Skateboards is the only place you will find equipment endorsed by Tony Hawk, as this is his own company. Visit www.birdhouseskateboards.com/ to see some of the selection they have for sale.
To buy veterinary medical equipment, people can find it at ShopMedVet. ShopMedVet is an online store for purchasing medical and veterinary supplies. Another great place to look for these equipment would be eBay.
I'd say the best route is to first find a karting team - they'd know / tell you wat to do and what is best to do for the area you live in :)
You can purchase Otari equipment online from personal sellers on the auction website eBay. You can also contact the Otari company directly to find a local seller.
The best place to purchase Bose equipment is directly from Bose. Also, one can find it at Best Buy, Amazon, Tiger Direct, and even thru Walmart. Deals can be had on eBay.
The locations in which one can purchase Golds Gym equipment for the home would be online in participating Golds Gym equipment stores, as well as any other retailers.
The Aerospace Parts Store is the best place to purchase Aerospace parts and equipment for the repair or production of Aeronautical devices including planes.