Finding economical 24 pin and 28 pin IC headers for adapter boards like ROM-el has been a significant challenge. DigiKey and Mouser stock on forked post headers, which are mainly designed for attachment of wires, not soldering to a PCB daughterboard. Aries Electronics offers the correct product, but they are almost $2.00 per piece, which is not sustainable.
Recently, I ventured into bulk purchasing of some components, like the 22/44 .100″ connector for C64/C128 cartridges, and the 6/12 .156″ connector for the C64/C128 cassette port. Given the success, I recently ordered 1000 each of some 24 and 28 pin IC headers, at much better prices. Of course, since I have no immediate need for so many units and I suspect others have the same issue sourcing these items, I’m soon placing them in the store.
Thus, if you’re in need of 24 or 28 pin IC headers, machine pin, low profile, check the store in a few days.