I guess it depends on what your idea of expensive is, does it have to be dinner, will you go anywhere for food and do you have the Entertainment book?
Fine dining wise-
Courgette are currently having a $75pp for four courses dinner deal or a $55pp for three courses for lunch.
Lake George winery has a beautiful open dining room overlooking the lake but I haven’t eaten there before, but you can wine taste while you’re out there.
Lark Hill great wines and have somewhat recently opened a restaurant, I haven’t eaten there before, but you can wine taste while you’re out there but it’s only available for lunch though.
The Flint at the Vines, I haven’t been out there before but if it was anything like the Flint @ New Acton it is definitely worth going to and it’s also on the Entertainment book card
Grazing – great food, probably easier to drive to during the day and if it’s good weather you can wander through their veggie patch. Also on the Entertainment book card
Pod food- Have fixed prices for their menu two courses for $55 or three courses for $68. Also on the Entertainment book card.
Versatile- bookings only, I’ve tried several times to get in, I should stop trying booking the day of. They have 1 Course: $35, 2 Courses $50 and 3 Courses $60
more Ala-carte with no set prices on their courses-
Ellacure- I recently went here for my birthday, it gets very busy but their food was really good.
La Cantina– one of my most favourite restaurants in Canberra, erring towards the side of a wee bit $$ but really great pasta (well the one that I had at least) and mains with a really warming atmosphere.
There are a ton of other restaurants I could recommend but they might be considered more of a ‘good for value’ or not really for a special occasion. Let me know on what you decide and if you still need help there are still many more restaurants I can rattle off. ^_^