Etsy is cuff link heaven! I've gotten many great gifts there for my dad and uncle. This may not be your style, but my favorite seller is White Truffle, which makes cuff links with tiny maps on them of anywhere in the world. There are plenty of more traditional styles on etsy too.
Re: Groom's gift-cufflinks
J + A [4-15-13] + JJ [1-22-14]