Where can I buy parts/tools online?

OEM Parts

These sites all have parts diagrams, some of them more useful than others.

kawasaki.com for part numbers - See OWNER INFO --> Parts Diagrams

Ron Ayers

Cycle-Parts

Bike Bandit

Cheap Cycle Parts

Parts

Dennis Kirk

Parts411

Old Bike Barn

MAW Online

Cycle Brakes

eBay
New, used, junk, bargains; it's all there on eBay. Make sure you know what you're getting, and pay careful attention to the shipping charges.

Fasteners

DESMOPARTS
Individual stainless steel fasteners. Also, complete stainless kits at their home page.

Pro-Bolt (tasty nuts)
Higher-quality nuts and bolts, aluminium and titanium bolt kits, and colored fasteners.

Bikebolts
Fairing bolt kits and other hardware in many colors.

Murph's Kits
See Replacing body fasteners/bolts

Junkyards, err... Used Parts

Our classifieds There are often several members with bikes they are parting out.

eBay Search ex250, ex 250, and/or Ninja 250.

Cycle Recycling Search Service

Cycle Salvage
Also sell new parts.

Northend Cycle
Also have a link to Nationwide Parts Dealers.

Cycle Therapy
Also sell new parts; on eBay, too.

dmoz.org Salvage Yard Guide

Bike Bone Yard
Used parts and complete bikes.

A & J Cycle Salvage
Also have new parts and accessories.

Additional used parts: Googling "used motorcycle parts" will turn up lots more choices. It may require some phone time, but if you can't find what you're looking for used for an EX250, you're probably not trying hard enough.