Well, actually, you would need to factor in at least 2 rental cars or 1 very large one.
However, they'll still need this if they don't plan to stay on Disney property. However, they could get away without renting by paying for a shuttle bus to take them to Uni and taking the Legoland Express (they'll need a taxi to take them to and from where it departs from, just off of the WDW property)...but, the Legoland Express only costs $5 per person.
Anyhow, point is, savings on hotel rooms ONCE daily car rentals are added (again, probably two cars or at least a large van...certainly not an economy compact) will add quite a bit to the daily cost.
They could easily get away with 3 rooms at Pop or one of the Values and be quite comfortable.
