Yes, assuming you don't need to connect anything together and that RAM is tinier than it really is, sure. At 28nm, 3megabits/square millimeter is what you get of SRAM, so an entire wafer only gets you ~12 gigabytes of memory.
And, of course, most of Cerebras' costs are NRE and the stuff like getting heat out of that wafer and power in.
Why not ddram?