For my 23rd birthday my parents bought me the .14 yellow gold Diamonds By the Yard. Ten, almost 11, years later I still wear this piece. As mentioned by another poster, you have plenty of time to collect. In addition, this piece comes up on the secondary market often; you may want to consider this route as well. http://www.beladora.com/store/505706_tiffany_co_elsa_peretti_diamonds_by_the_yard_pendant_in_18k
Thanks!
I hope mine comes soon, maybe I'll save up for it.