At the age of 37, I've realised it's better to buy a few nice pieces and wear them constantly rather than lots of cheap things. I look terrible in cheap clothing anyway, it's not cut for my shape and never fits properly anyway. I'm also a fabric snob, but that's more because synthetic fibres give me a rash.
So, the bulk of my wardrobe comes from COS and Whistles with a few bits from Sessun, Comptoir des Cotonniers, Sandro, J Crew and Isabella Oliver.
I also buy a few 'designer' bits and pieces from My-Wardrobe and Liberty too. Shoes come from a variety of places, summer sandals tend to be cheap though, brogues, ballerinas and ankle boots less so as I'm on my feet for a lot of the day and well-made comfortable footwear is expensive! Tights are from Falke as they last for ages and are more cost effective than dozens of pairs from M&S.
I think Zara is good for accessories but i've given up buying skirts and dresses from there as they're always too short. In fact, skirt lengths have made nearly all high street shops out of bounds for me. I have good legs but I don't think mid-thigh is an appropriate length for work!
Aside from the COS clothing, most of the clothing I own have been purchased with a discount voucher, on sale/during a promotion or from eBay. Orla Kiely's summer sale proved to be rather fruitful, I purchased a mac which I've not taken off since I got it - definitely the best summer 2012 buy!
PS. I plan my wardrobe, and shop twice a year with the odd purchase here and there as needed.
I realise and know I'm in a very lucky position here.