Here's the thing, Brazilian Mahogany is CITES restricted (basically it can't be imported or exported), the genuine article is (notionally at least) hugely expensive,...but despite all that hardly anyone in the UK actually wants the stuff!
Luthiers seem to prefer Honduran Mahogany (plus they only buy in tiny quantities), antique restorers prefer Cuban Mahogany (plus there are so few of them left anymore and they make so little money that they're not buying much of anything), and Mahogany generally is so far out of fashion that even though furniture makers love working with it, they can't convince any of their clients to actually buy anything made from Mahogany. The one opportunity I can think of is premium garden furniture, like really well made steamer chairs and the like. But the comparison you'll always be battling against with garden furniture is Asian imports made from plantation grown Teak, that sells for less than I can source the materials.
EBay has plenty of Mahogany salvaged from broken up, low grade Victorian antiques; plus there's also loads of people on Ebay selling Khaya, Sapele, and other African timbers but calling it Brazilian Mahogany.
So which ever way you look at it, the market for Mahogany is in a bit of a mess at the moment.
But if you do find a buyer at anything like a reasonable price then please let me know. I must have at least 20 or 30 cubic foot of really prime Brazilian Mahogany, as it's pretty unlikely anyone will ever commission any furniture from it, I'd be only to happy to let it go!
In all seriousness, if you could get £100 a cubic foot for it then my guess is that you'd be doing pretty well.