This is easily answered in theory, but difficult to judge
in practice. The easy answer is that a non-profit should not
have making money as a purpose nor should it provide an investment
return to its members. But in these times of reduced funding,
many groups are involved in some form of money-making activity
through sales. As long as the sole and primary purpose of the
organization does not become making money, it can continue with
incidental money-making activities. But when an organization's
commercial activities become so dominant as to overshadow the
purposes for which it was established, trouble might arise. The
rules for charities about business activities are quite technical.
Any charity which regularly sells goods or services to the public
should carefully review its situation.