diyleduk sells heat sinks, though they may be better suited to Samsung strips.
You would be better running more EB gen 3 or cree J series on aluminium U profile.
You can get that cheap from aluminium warehouse in UK.
If you run more strips you will power them softer and wont need expensive heat sinks.
With the price of EBs or cree J series its worth doing.
Maybe look at
@diggs99 build.
I like the cutter.au J series because they are 48v and I think you can run them at 50w on just U profile but the negative is they are from Aus , they used to have a great price break for quantity, they don't seem to have that anymore but it might be worth asking mark. Depends on how big of a light your building.
Aluminium warehouse will also cut your lengths for very little
Wide Range Of Aluminium, Steel, Brass, Copper & Easyfix Products. Order Online Today! Only Pay For What You Need With Our Custom Cutting Service. Get Up To 10% On Bulk Orders. Metals Cut To Order. Fast, Convenient, Secure.
www.aluminiumwarehouse.co.uk