Korin, eh? I'm going to assume NYC, then.
If you're looking for Western handle knives, I'd suggest either the Misono UX-10 or the Masamoto HC. The Misonos are highly styled, comfortable, stainless steel knives. The Masamotos are slightly more traditional and made with really wonderful carbon steel. Masamoto are reknown for excellent quality and great feel in the hand. If you're fiancee loves carbon, get the Masamotos.
Another stainless line available at Korin is the Masamoto VG, which are styled just like the HC and have the same wonderful feel. The Misonos are more highly regarded than the Masamoto VG, and actually do hold an edge a little better. Yet another line around the top of your price range is the Nenox G Series. They're beautiful knives, but to my mind not worth the money. You can't afford the S series, so don't ask.
Since your fiancee is a pro, think 270mm gyuto, 270mm sujihiki (slicer), and 150mm petty. Korin doesn't show the Masamoto santoku on its website, but I know Masamoto makes only one in the HC line (180mm); and the Misono UX-10 is also 180mm. If he wants a santoku, he wants one and should have it. If you're planning a surprise, you might consider a 180mm gyuto, the shape is actually slightly more versatile than the santoku's in the hand of a skilled cook.
If you're looking for traditional Japanese handles, I'd suggest the Masamoto KS (hongasumi) series. But since the blade profiles you're talking about are basically western, I'm going to assume he wants the western style handles and blade profiles. Aritsugu (suggested by Chris) do not make Western handled knives -- and even some of their double edge designs are not lefty friendly. Furthermore, the Aritsugu A series is very difficult to sharpen. Unless your fiancee is a very skilled sharpener, don't even think about it.
As big a fan of several e-tailers (including Japanese Chef's Knives) as I am, I'd buy from a brick and mortar store in the NYC area as it makes returns possible. If you want suggestions besides Korin, I can make one or two. Two very good lines available in NYC from other retailers are MAC Professional and Sakai Takayuki Grand Chef. IMO the MAC Professionals are great knives, but not as prestigious as the other knives mentioned. The Sakai Takayuki Grand Chefs are really terriffic knives. However, buying them (from Seito Trading) is going to be a little more complicated than going through Korin since Seito will have to order most of the sizes and shapes you'll want.
Almost all of the better Japanese knives are delivered with right-handed edge profiles. Any good sharpener can move the symmetry to neutral or left handed. Korin charges $25 per knife. If you ask, Korin will also tell you not to sharpen to a neutral (50/50) symmetry. While everyone's entitled to an opinion -- that one happens to be BS.
However, since the quality of sharpening is as important (maybe more) than the quality of the knife itself, I suggest you buy your fiancee a really good set of stones and an appropriate steel to go with his new knives, but not from Korin (Korin will tell you not to steel Japanese manufactured knives -- also BS; and they're stone choice is neither good nor well priced). If you decide you want to look into this, let me know which knives you'll be buying as the top of the stainless set is slightly different than the top of the carbon set. The whole thing will run around $175 - $275.
Another nice addition to the set would be the MAC bread knife sold at Korin. You don't think of there being much difference in bread knives, but the MAC is worth the $85 Korin wants for it.
FWIW, as a lefty with professional knife skills, I'd want the Masamoto HC knives. But I love carbon and have lived with it for years. My suggestion is that if he's not already a carbon guy or isn't specifically interested in it than get the Misonos. Each of these lines is as good as mass produced knives get.
Don't forget to tell the big lug I said, "Congratulations. He's not good enough."
Best wishes,
BDL