How any baseballs are used in the NBL a year for an average team?

The average team goes through a lot of baseballs: around 18,000 a year!

"Each major league baseball team uses about 18,000 baseballs each year."

DiscoverTeenergy
http://www.discoverteenergy.com/giftrap/2004_02.html

"Each major league baseball team buys about 18,000 baseballs every year."

Chiropractic eMarketing Solutions Newsletter
http://www.chiropracticemarketingsolutions.com/archieves/july2002newsletter.htm

"Every major league baseball team in the U.S. buys about 18,000
baseballs each year."

David Ohlin: Baseball Trivia 
http://www.geocities.com/davidohlin/softball/trivtriv.htm

"Rawlings ships 600,000 to 700,000 baseballs to the Major Leagues each
year. The average life span for a new baseball in the Major Leagues is
six pitches."

CJIS: History of the Baseball
http://www.cjis.com/history.htm 

Google search strategy:

Google Web Search: "team uses" "100..100000 baseballs" year
://www.google.com/search?hl=en&q=%22team+uses%22+%22100..100000+baseballs%22+year

I hope this is helpful. If anything is unclear or incomplete, please
request clarification; I'll be glad to offer further assistance before
you rate my answer.

Best regards,
pinkfreud