I've never seen an Oak Bays in a store, I've only ever seen it advertised at the Mulberry website at the RRP; I've not ever seen it at the website on sale.
It may be possible to pick one up for second hand via ebay at a reduced price. Obviously there's the issue of authenticity when purchasing from ebay but there are members here who are great at authenticating bags.
Best wishes with the purchase. I have a printed Oak Bays and it's my favourite bag. I love it!
You can wait for a 10% day - by getting a Fraser or Harrods ctore card (at Harrods all concessions take part in 10%, in Fraser not always). It is unlikely to get them for even less then 10% (I have been looking at those for ages, and got an oak one from the older collection, before they went up in price).
What they sell in outlets is very defferent "printed", pretty ugly imo.