If you can collect, I would suggest trying Wealdon oak in Edenbridge, its a haphazard yard, but if you dont mind spending a bit of time finding what you want there are some gems to be found at good prices.
Lenham Oak, http://www.lenhamoak.net/Welcome.htm, a few years ago i was after a piece of good oak for a boat keel, i told them what i needed & they cut it to order 18ft of 8"x2" quartersawn & as few knots as possible. The piece they cut was perfect & grain like an arrow. And dirt cheap.
They seem to cut mostly green stuff so you will need to season it but its good stuff & nice people to deal with.
I paid about £28.00+vat per cu ft for 1" boards, but that was a while back for S/E kiln dried Euro oak. The stock wasnt the cleanest but since I was able to select out of 3 packs it didnt matter.
