Perhaps the most famous is Sheena Iyengar’s 1995 “jam jar study“, which showed a 4x increase in options decreased purchases by 85%.
Iyengar’s study is not alone. Barry Schwartz’s excellent book The Paradox of Choice covers the problem in detail. Of particular interest is his discussion of how choice affects buyer’s remorse. The more choices you consider, the more likely you’ll be to regret your decision, and the less satisfied you’ll be.