Depend what you want to do with it. NDA can be used for many purposes and situations.

Quickest one - go online to get a template and modified from there. You may purchase or search for free for a few templates in different structure to suit your needs. (this provided you are confident to modified by yourself or your colleagues).

If you are not confident of the above, the next option is to pay some money to a legal person to help to produce some (actually s/he also go to Internet to get few and modified for you). If you find getting professional may be too expensive, look for freelance.com, upwork.com, fiverr.com ... for a cheaper one (but quality will depend your luck).