The aim of this article was to identify the role of good mutual relationships with offerors for final purchasers, as well as define the meaning of the perception of offerors in the scope of listening to purchasers’ opinions and profiting from purchasers’ readiness to cooperate for the specificities of the prosumeric activity. A deep analysis of the world literature was used to prepare the theoretical part of this paper. The results of this analysis confirm the existing cognitive gap and research gap regarding mentioned aspects, including energy market. Empirical studies were conducted to reduce identified gaps. The survey method was used to collect primary data. The collected data were subjected to quantitative analysis, during which statistical analysis methods and tests were applied (Pearson chi-square independence test, V-Cramer factor analysis, Kruskal−Wallis test (KW), and exploratory factor analysis). The results of the statistical analysis and testing allowed the three research hypotheses formulated to be checked. Between the significance of good relationships with offerors and their perception, a statistically significant dependence was identified for all groups of offerors. The perception of offerors was a feature differentiating respondents’ opinions about the significance of good relationships with offerors for the two following groups: producers and traders. Additionally, the perception of offerors was a feature differentiating forms of prosumeric activity of respondents only for three interpurchase behaviors. The results obtained have a visible cognitive and applicability value. They contribute to the theory of marketing, as well as possibly facilitating the formation of good mutual relationships between offerors (including offerors of energy) and final purchasers as key partners cooperating with offerors in the marketing process. The approach presented in this paper has not been studied and analyzed so far, either in theoretical or in practical terms. This fact confirms its originality and value.