Sustainable aviation fuel (SAF) is a key component for the defossilization of the aviation sector. The economic feasibility of SAF production is typically evaluated through techno-economic assessments (TEA), with the Minimum Jet Fuel Selling Price (MJSP) serving as the key economic performance indicator. Comparing MJSP values across different SAF pathways is challenging and potentially misleading due to differences in modelling assumptions, estimation methods for key variables, and their underlying relationships. This study aims to contribute to a more comprehensive understanding of the economic feasibility of four prominent SAF pathways: Hydroprocessed Esters and Fatty Acids (HEFA), Pyrolysis-to-Jet (PTJ), Alcohol-to-Jet (ATJ), and Fischer-Tropsch (FT). We employed qualitative and quantitative methods, including meta-analysis and variable harmonization, to analyze a wide range of TEA studies from the literature and investigate the factors contributing to MJSP variation for these pathways. Our findings reveal that feedstock cost is a primary driver of MJSP variability across all pathways. Moreover, regression and harmonization analyses uncovered complex interdependencies among economic variables often underexplored in individual TEAs. Key sources of MJSP variability include methodological differences in by-product credit valuation, process design choices, capital cost estimation approaches, and financial assumptions. Recognizing and addressing these factors offers strategic opportunities to improve the techno-economic performance and comparability of SAF pathways. Notably, the PTJ pathway emerged as a promising alternative for non-food feedstocks, and all pathways demonstrated improved economic outcomes when integrated with existing industrial infrastructure. The analytical findings of this study provide a robust empirical foundation that can be leveraged by future studies aimed at policy analysis, as well as for project budgeting and investment decisions in sustainable aviation fuels.