I'd buy that Snadger. If you bank on around 4 per plant it will give you an idea. If you want more shallots but smaller try saving them from the higher producing ones.
The more space you give them the higher the yeild as well but it gets to be a a point of diminishing returns. I usually give them around a foot apart in the rows and about 2ft between the rows but I sow a row of carrots inbetween them ( trying to confuse the carrot fly with onion smells) and I think I planted about 45 out this year so Mrs G had better learn to pickle