microwave caught fire inside when accidentally run empty, rusting inside. replace or repair?

i have a homemaker 20L microwave oven with some pushbutton controls, i used it for several years maybe 3 or 4 years, i had it repaired once they replaced a filter or paper inside when it sparked mybe a couple of years ago, it has developed some rust from the inside looks like the paint chipped or flaked off, removing the white paint coating , i used it mybe a 2 to 3 weeks ago i accidentally turned it on for 30 second setting without anything inside it caught some spark and then saw fire inside so i unplugged it immediately with lots of smoke when i opened it, i never operated it since, i put some tape on the plug so no one may use it, afraid it can cause a house fire or danger to life, so what i did was to order online just hours ago with a new microwave as i see they are cheap now, after that i searched online saw some different views about it, some they its easily repairable, by replacing something than throwing it away, some say to throw it away and buy a new one. with this situation of spark fire incident with the rusting issue. if i bring it to a repair shop i'll spend for it, if i buy a new one ill also spend on it, the price difference might not be that much, i can still cancel it or go through with my order? what is your advice?