The shopping bug bites

Ugh, I'm agonising over whether I should get any or all of these 3 dresses I saw while wandering around Regent St yesterday:

• Grey strapless sack hippy dress with pockets (hmm the description doesn't make it sound very attractive), £55, Cos
• Black empire line dress, £39, Cos
• Yellow and black floral print silk dress, £75, Banana Republic

Gaaaah.