Amazon Basics has 25lb pretty cheap, it’s currently at a discount as deal of the day https://www.amazon.com/AmazonBasics-Rubber-Encased-Dumbbell-Weight/dp/B074DZGRMG/ref=sr_1_6?dchild=1&gclid=EAIaIQobChMI5s6JirTp8wIVwfezCh0jggQ3EAAYASAAEgKQ3fD_BwE&hvadid=322134833695&hvdev=c&hvlocphy=1022698&hvnetw=g&hvqmt=b&hvrand=2917712292487719911&hvtargid=kwd-342173679829&hydadcr=15186_9872021&keywords=amazon+weights+dumbbells&qid=1635297012&sr=8-6

A bit late but you can get these on Amazon for a much better price, they are OOS but you can still order them: https://www.amazon.com/dp/B074DZGRMG/

Depending on weight it ends up being $60-90-ish, much more reasonable price wise although it won't be the same quality as the OTF ones.