depends. I could be very wrong, and it could truly be the inverter, in which case it would be better for you to get a new laptop, as the inverter is soldered onto the motherboard. Labor alone for replacement from anywhere will be expensive.
If it is the monitor, I've seen Dell lappy monitors go for about $70. Depending on where you go to have it changed, the labor cost could make it not worth the new monitor.
How old of a lappy do you have?