In general, your starter volume is more important than your starting cell count. So long as you keep the yeast in suspension(if you don't have a stirplate, just give the vessel a good shake every couple of hours), they'll continue to reproduce until they have the right numbers to process the sugars around them. If your starting count is a bit low, it might take an extra day or so to get to your ideal number, but it will still get there. For 150-200b pitching rates, a 1L starter is probably about right just to be on the safe side.
So long as you've got at least 10mL(about an 1/8th of an inch in a 1quart mason jar) of yeast solids on the bottom of your storage vessel, you've got plenty of washed yeast to make a 1L starter.