This study examines price convergence in the regional primary timber market in Poland. Although timber in the State Forests is sold under a unified institutional framework and standardized assortment classification, persistent spatial price differences remain. Understanding these mechanisms is important for improving the efficiency of the timber sales system and reducing revenue losses associated with spatial price disparities. The aim of the paper is to assess timber price convergence using forest districts of the Regional Directorate of the State Forests in Katowice as a case study. Quarterly nominal timber prices (PLN/m³, net) for 2005–2024 were analysed, focusing on economically important pine and oak assortments, particularly large-sized timber (WC03) and medium-sized timber (S2A). Three complementary measures of convergence were applied: β (price catching-up), σ (changes in price dispersion), and γ (changes in relative price rankings measured using Spearman’s rank correlation coefficient). The results indicate statistically significant β-convergence across all assortments, implying faster price growth in forest districts with lower initial price levels. However, no evidence of σ-convergence was found, as price dispersion did not decrease over time. The γ-convergence analysis revealed limited changes in price rankings, particularly for large-sized oak timber, indicating persistent relative price differences. The findings suggest that a unified sales system contributes to convergence in price dynamics but does not eliminate spatial price differences, which should be considered when formulating sales strategies to avoid pricing and revenue inefficiencies.