Squarespace CSS for Variable Image Dimensions

I run an artist's cooperative gallery on Squarespace Commerce and our shop automatically crops every product photo into a fixed aspect ratio. Because our items are fine-art prints that come in many different aspect ratios, the forced cropping ruins the composition and confuses buyers about sizing... (Budget: £10 - £20 GBP, Jobs: CSS, HTML, JavaScript, PHP, Squarespace, User Interface / IA, Web Design, Web Development)