Zuca has a back to school sale with some selected models on sale for $99 (Select Designs w/Black Non-Flashing Wheel Frame, code: BTS19 valid through 8/19/19). This seems like the lowest price I can find (normally they are $168, not sure how cheap they get throughout the year)
While originally designed for figure skaters, Zucas became a fad for elementary and middle school kids (I guess, the whole point is that two pairs of wheels allow you to roll down the hill). Overall looks like a sturdy bag. If you kid doesn't beg you to get one and you're not a skater you probably don't need one.