Baby Bathtubs... worth it?

I know they are only like $20 at the store, however I was reading Moms on Call and they suggest just bathing baby in the regular tub. I think I might try this when he is still a newborn, but I have a very large garden tub in my master and might just get in with them for extra precautions. Someone already bought me a tub off my registry and someone else made a mistake and also bought me one. So if I could return both for $40 I’m thinking I could get other essentials like diapers etc is it just seems like a waste. Has anyone tried this method? Also when can I just shower with my baby?