Bimatoprost eye drops are primarily used to manage glaucoma by reducing pressure inside the eye. A notable side effect is increased eyelash growth, leading to its cosmetic use for longer, thicker lashes.  

Finding the "lowest price" for bimatoprost requires careful consideration. Prices can vary significantly depending on the brand (e.g., Lumigan), the concentration (common ones are 0.01% and 0.03%), the volume of the solution, and where you purchase it. Generic versions of bimatoprost are available and are typically more affordable than the brand-name Lumigan. 

To get the best price, it's advisable to compare costs at different pharmacies and inquire about generic alternatives. Online pharmacies might offer competitive prices, but ensure they are reputable and require a prescription, as bimatoprost is a prescription medication. Discount cards or pharmacy membership programs could also help lower the cost. Keep in mind that the "lowest price" should not compromise the quality or authenticity of the medication.