I think air driven sponge filters are probably the best bet for shrimp breeding tanks. Bio load is usually low in shrimp only tanks so the sponges are more than adequate. HOB and canister filters will work but I prefer to save my money on those items and instead purchase more shrimp. If you decide to use an external filter, you should invest in some sort of covering for the inlet of the filter to keep small shrimp from being sucked into the filter.
At that price, I would still get the Ehiem and save it for use on another tank.
At that price, I would still get the Ehiem and save it for use on another tank.