The coolant level sensor is a pretty cheap part (under $20 ), and an easy DIY.

You'll need to drain some coolant to replace it, but the procedure is pretty much just drain coolant, disconnect sensor wires, remove sensor, wet the o-ring on new sensor with coolant, slide in new sensor, re connect, refill system with coolant, replace coolant cap, run engine, top off coolant, re-replace cap.