Flatland specific parts have very limited availability, usually they are few years on the market and the brands seem to discontinue production very fast, it's a niche market.
Finding a sprocket for that cranksets won't be easy, if you're in the USA try Bmxmuseum website sales section, they usually have pretty unique stuff their.
Summing it up, yeah you are better of selling that cranksets yo someone who needs it for a new school build and get a good old classic bolt drive of spline drive cranksets with an axle that fits EuroBB.