When I first moved to Calgary I was quite scared that I would not be able to find any Vegan/Vegetarian restaurants. During my hunt I found "The Coup". Although their no reservations policy can seem to be slightly annoying at first, I've come to realise it's now my favourite system; It gives you a chance to 'try out' a restaurant without any real commitment, if you walk in take a look around and aren't really feeling it, you can leave without feeling like you're forced to take a table and stay.
The Coup has been one of the better food experiences I've had in Calgary and have returned multiple times.
I had the flatbread the first time I was there, it was absolutely delicious! All in all I don't feel like it's really expensive whatsoever, but then again I do have a very different view of expensive than most people :P
I would and have been recommending The Coup to everyone I know, it's an awesome place to go, and a great introduction to vegetarian food if you haven't made the leap to try it before.