There was a warehouse/shed like place I used to go to between Bath and Bristol for French farmhouse sinks, almost the same as a Belfast. Brand new they were 100.00 'ish.......I think the price had a lot to do with how much the bloke had drunk at lunchtime. Try google put in west country or something with belfast/French kitchen sink.
Alternatively, nowadays I use the Ikea Domsjo to throw in and impress the lady buyers. Costs a bit more, but it'll be new and won't need cleaning. If you do need to clean one "Barkeepers Friend" works a treat after a squit of Cillit bang.