Take two dresses

It's always the way - you go out looking for a certain something but you don't can't find it! At the Temperley Sample sale last week I hunted high and low for the Cecily mini tunic dress - in my head I thought it would tick all the boxes for SS10. But it wasn't there, there were a few other similar dresses but they just were not in the right colour. I didn't want to settle for the second best so I came away empty handed - gutted. I am trying to be more strict with my shopping as I have had a run of impulse buy's the last few months. I've been letting the delights of W1 go to my head and being able to access lovely shops again. So I turned to ShopStyle to see if I could hunt it down. They have it on The Outnet but look who else has something that's a fraction of the price. Top Shop :-D 

OK not the exact dress and not the same detailing or fabric, but pretty close colour match and with the saving I could go on to buy sooo much more. What shall I do, go for quality designer dress or high street knock off?