I also thought 99, but it is heavy. Aluminum 201? Singer 301 - although I've never seen one with a hand crank. Elna Grasshopper would be ideal, self contained with the case also being the table, sturdy, has a low gear, but heavy. Not sure if it could be fitted with a handcrank. The candidate machine probably needs to have droppable feed dogs for darning. I don't know if a Singer 127/128/27/28 has feed dogs that drop, but this can a be hand crank. Geeze! A Pfaff 130 would fix anything, can be handcranked, but heavy and wouldn't approve of sand. I have seen Singer 221 Featherweights with hand cranks, but as you said, not cheap unless somebody donates.