The technology for (purely) microwave ovens is well established and the big difference between your 20 y.o. 1000 watt microwave when it was brand new and the current 1000 watt units is that the new units use those 1000 watts more efficiently. So the main cost difference then is the name brand of the unit and the range of cooking and programming features.

Thanks.

I just got rid of an older (20 years) huge Tappan microwave. Paid a lot for it 20+ years ago. Anyway it was 1,000 watt and it heated up food great all the way to the end. Started having trouble with door switches, and fuse blowing so I decided it was time to get a new one. I just bought a Magic Chef 1.3 cu ft 1000 watt microwave and notice that when I heat something up, it takes many more minutes to get the same result as my old microwave. Is that supposed to be. Of course, it is not made nearly as well as my old one but I thought it would tie me over till I looked for a better one.