Congratulations on your new horse! I no longer have a horse, but if I did, I'd actually splurge for the bridle. If you buy Hermes, it's all about the leather, and the bridle is something you'd handle everyday, clean and polish regularly. If you already have a bridle, perhaps a halter with a nameplate. If you're looking for something small, maybe the stirrup irons, especially if they have the subtle clou de selle symbol on it somewhere. Or spurs if you use them. Nothing that you'd end up losing too easily (crops, hoof picks, brushes, polo wraps seem to disappear in any barn) and nothing that screams Hermes like an orange saddle pad or anything with a big H on it (people on the horse sites are right, H is overpriced for tack and equipment, and I'd personally rather not advertise that I bought my horse something from Hermes, lol).