Flooded Basement

I recently refinished my basement in Central New Jersey. Covered cinderblock walls with studs and drywall, installed a DRICore subfloor, and carpeted.

Two weeks later we had a major rain storm (4.5 inches of rain) and my basement was flooded. About three weeks before the flood we had a snow storm (20 inches) which finally melted about a week before the rain storm, so the ground was saturated.

We do not have a french drain or sump pump. The only history of flooding in my home was once during Hurricane Floyd and this storm. I had 3 basement waterproofing company's quote me upwards of 6K to cut my walls, dig a perimeter trench in the floor and install a ditch and sump.

Is all of this necessary, or will a ditch and sump alone be enough considering the infrequency of flooding in my home?

One last note, a week after the flood we had another major storm (4.25 inches or rain) and no flooding occurred. Also, no water appeared to seep through some of the walls that are still exposed.