As with most products purchased in the USA, any State having a sales tax will have retailers charging taxes on new and used tennis racquets; some secondhand or other re-sale stores may be exempted from having to charge sales tax. Many out-of-state retailers are not required to charge taxes on purchases made from customers in a State where that retailer does not have a physical presence (of course, the downside is that any shipping, handling, and insurance costs may offset any tax savings).
In the old days tennis racquets were made of wood or metal. Technology has enhanced tennis racquets, and has made the game easier, and gives the athlete a larger chance to do more with the ball.
Tennis racquets are sold at almost all major sporting goods stores, including Dicks and Sports Authority. Major retailers like Walmart also carry tennis racquets.
They're store-bought racquets with the excepts of Rokkaku in which the coach personally designs each player's racquet. For real-life Prince of Tennis racquets, they're occasionally stocked as official merchandise that can be found on the official Prince of Tennis website or in anime conventions.
Adult racquets are usually longer and heavier than junior racquets
http://tennis.about.com/od/racquetsballsstringing/a/evolmodracquet.htm
Babolat is a French sports equipment manufacturer that produces strings and tennis racquets for tennis, badminton and squash. Famous sportsmen like Roddick, Nadal or Clijsters use their racquets.
At the Tennis Express stores. They sell racquets, clothes, balls, tennis books, tennis DVDs, sunglasses, bags, and more.
No you can bring as many as you want.
Yes, you can keep more than 10 racquets in a Wilson tennis bag. The company makes several bags that hold up to 12 and 15 racquets. As with any racquet bag, you will want to check to see if there's enough room for clothing, accessories and your racquets. It may be better to err on the side of getting too large a bag.
Yes, Raquet Ball
One Babolat tennis bag that holds 12 racquets is the Aero Racquet Holder; another is the Team Racquet Holder; and finally the Club Line Racquet Holder. These are the largest bags Babolat makes.
There are many companies, worldwide, that manufacture tennis racquets (n.b., finding all of them would be time-consuming; listing only a few would be unfair to the others, and could be construed as advertising, which is against the rules of this website).