$500? Not unless that bar is hollow and has BB'ing drugs, and a needle, stored inside for our doper friends. Maybe $29.95, as a "Seen On TV" special offer. Reduced to $19.95 if that doesn't sell.
There are hand held springs (still used in Europe) and rubber stretch bands also that are effective. Both are adjustable in resistance.
Three times the muscle growth over weights, from their research. All a total scam...of course.