If your boat is an american model try fpmarine.com
I needed a new lower dash section for our SeaRay to allow me to fit some extra guages and SeaRay in the USA couldn't/wouldn't supply a blank without the standard holes pre-cut (despite the best efforts of Marina Marbella to try for me) so I used the power of the internet to find their supplier in the USA but loads of money was required but I also found "Flounder Pounder" FPMarine.com in the USA as well as loads of new stuff they stock second hand and surplus OE stock.
I ordered a dash from a much bigger SeaRay than mine which had a large blank area in it and cut out the new panel I needed from it and all much chaeper than I thought. Very helpful USA company, plus the $ to £ rate helps!