"Niche" and "affordable"? Not an easy thing to find. However, I'd stick with the Parfums de Nicolai brand (check out LuckyScent.com), they have very good niche scents at a very reasonable price (under $100).
If you like sweet scents, particularly L'Instant (you've got good taste), I'd try New York, which is a woody, spicy oriental that's kind of sweet, or Nicolai Pour Homme, which smells tart and somewhat sweet to me and reminds me a lot of Caron's Le Troisieme Homme.
P.S. Expect to get a ton of responses to your thread.