Though synthetic accessibility is an important criterion, often particularly early in the drug discovery pipeline molecules to be tested are selected based on price, effective availability and ease of synthesis. Given that, we next examined the relationship between SA metrics and price. We compared the price in the Mcule catalogue for the compounds in the PC dataset to our set of SA scores. All SA metrics had only a weak correlation with price (see Figure ), with PCC values ranging from 0.16 to 0.35 and SRCC ranging from 0.16 to 0.41. Even a combination of all scores in the form of a linear regression model still performs poorly when trying to predict the price, with a PCC of 0.46 (see Supplementary Figure ). These numbers agree with the value of 0.3 reported by Fukunishi et al. and suggest that the synthetic difficulty Figure . Expensive compounds tend to exhibit larger Synthetic Accessibility (SA), but SA metrics are unhelpful for price prediction as they correlate weakly across all price ranges. Distributions of different synthetic accessibility estimations (SAscore 10 , SCScore 11 , SYBA and RAscore 8 ) for catalogue compounds of different price ranges. Last price range comprises all compounds with prices above 80$/mmol. of a molecule may have only a small impact on the final cost of a compound. Although this conclusion seems counterintuitive, there are many reasons why this might be the case, for example, compounds that are in high demand will benefit from economies of scale, thus lowering their price regardless of their synthetic accessibility. For the same reasons, it is not unusual to find complicated building blocks at low prices in multiple catalogues, which allows the easy synthesis of otherwise difficult compounds. Nevertheless, while cheap compounds comprise both easy and difficult compounds, in general, expensive compounds tend to be less synthetically accessible than their cheaper counterparts (see Figure ).