investing in a watch

Hi, My husband has a fantastic collection of Swiss timepieces but has recently been looking into not only purchasing watches that catch his eye but, in particular, 'investment' pieces. He is too proud to ask for help, so I thought I would take the liberty of asking all the great watch experts...

Yes hello I have $2,500 I'm looking to invest in a watch. I would like to buy something and resell it for more? Is there any advice you could give me? Thank you Clay