Background: Invasive Aspergillosis (IA) remains a leading cause of morbidity and mortality in immunocompromised patients, particularly in Low- and Middle-Income Countries (LMICs) like Pakistan, where delayed diagnosis due to limited culture facilities and high costs of treatment drive poor outcomes. We assessed the diagnostic accuracy and comparative cost-utility of multiple non-culture assays in Peshawar to identify the most sustainable rapid diagnostic strategy. Methods: This prospective, one-year (Jan–Dec 2025), observational study at a large tertiary hospital in Peshawar, Pakistan, enrolled 485 consecutive high-risk patients suspected of IA. All subjects were tested using serum Galactomannan, plasma Beta-D-glucan, Aspergillus Lateral Flow Assay (LFA), and IgG/IgM serology. Definitive diagnosis was composite EORTC/MSGERC criteria. Accuracy metrics (Sensitivity, Specificity) and cost-per-result were compared. Results: Of the 485 patients, 62 (12.8%) met the criteria for IA. GM showed the highest sensitivity (79.0%) at a cost of 35$. The LFA was the most cost-effective at 12$, achieving the highest specificity (97.7%) but lower sensitivity (61.3%). BDG (45$) and serology (20$) performed inferiorly with sensitivities of 74.2% and 50.0%, respectively. Notably, the combined use of LFA and GM yielded a high overall sensitivity of 90.3%. Conclusion: In the high-burden, resource-constrained setting of Peshawar, the Aspergillus LFA represents an economically viable first-line approach for rapid IA detection due to its high specificity and low cost. While Galactomannan remains the most sensitive individual assay, its higher expense challenges sustainability. These findings support integrating LFA-based assays into LMIC diagnostic algorithms to accelerate antifungal stewardship.