The European Union’s Omnibus Pricing Directive mandates that traders disclose the lowest price offered in the previous 30 days, aiming to curb inflated reference prices and enhance consumer protection. We present an experimental test of this policy’s behavioural impact. In a pre-registered online experiment with 500 UK consumers (where the Directive is not yet implemented), we examined whether displaying a lower prior price (the “Omnibus Price”) affects willingness to buy, and whether this varies by product type or financial information avoidance. Across all goods, the Omnibus Price significantly reduced purchase intentions, with a larger effect for utilitarian than for hedonic products. No evidence was found that financial ignorance, measured via the Financial Homo Ignorans (FHI) scale, moderated the impact. Our findings provide a behavioural baseline for policymakers and suggest that mandated price transparency can meaningfully dampen consumer demand for products marketed with inflated reference prices.