That was my first computer! Under 300 my ass! First one we got was 400 plus 100 for a cassette drive. In 1981, that was some serious dough. It was an early production unit and the sound and video was terrible, poorly shielded RF cables. We exchanged it for a different unit at a different store, $399.99 for both the computer and drive.
3, 583 bytes free if I remember correctly. Almost all computers have more than 3, 583 megabytes > a million times improvement.
The CPU was a 8 bit 6502 running at 1 megahertz. No multiply or divide on the chip and most machine code operations took 4-5 cycles so you would get about 200, 000 8 bit operations per second and would be lucky to do 2000 complex integer 32 bit multiplies and 64 floating point operations per second? Well you code write a program to accomplish it and it would probably do a few per second compared to giga flops now available on a graphics card.
One thing about the ad was true. Since there were no games at the time available and exchanging pirate software was done with the sneaker net you really did have to learn to write your own games. I was a paid published author of a computer program by the time I was 14. I think I made just enough money all told to get an electric trolling motor for the family canoe!