Pride, and the associated emotion of self-love and desire for honour, were discussed extensively in 18th century ethical texts (Paley, Shaftesbury) as being motives for good when trained properly and for evil when badly trained or present in excess. Pride, and the desire to behave in a manner appropriate for high station, was conceived as a motive for charity, which was considered behaviour appropriate, and in fact, de rigeur for the upper classes (noblesse oblige). Thus as Elizabeth discovers when she visits Darcy's estate, Darcy's pride leads him to treat his servants and poorer neighbors with great fairness and charity. Elizabeth's own pride, leading her to refuse to marry for mercenary reasons or to toady to the rich is also a virtue in moderation. More pride would have led Lydia not to elope and Kitty to have behaved better.
Mr. Darcy exhibites "good pride" when he selflessly pays the dowry for Elizabeth's sister so that she could marry Mr. Wickham and save the Bennett family's reputation. Additionally Mr. Darcy endeavors to keep his good deed a secret. Elizabeth Bennett exhibites "good pride" when she fiercely defends her family to Mr. Darcy when he asks her to marry him (the first time) and then strongly crtizeses Elizabeth's family's economic situation and social standing. Her family values and pride run so strong that she gives up complete financial security to defend her family.