I saw a great thread about this ages back but can't seem to find it.
What did you not bother to buy the second time you had a baby?
And what things were better than you thought?
With DS I found I barely used his baby bath and he soon grew out of his Moses basket so I think I'd look for an alternative for downstairs naps.
I don't think I'd get a high chair again, it took up too much room and he outgrew it so second time round I'd get a mamas and papas seat that you attach to a chair that does the same job but adapts as they get older
I found muslin squares more useful than I thought they'd be!