 New-old-stock units have sold for as much as US$180 and used tubes for over $100, more than the original price of the radios that use them.Collectors rarely, if ever use these tubes for fear of burning them out.Sets that use the costly WD-11 and UX-199 tubes can be modified to use the 1A5/GT octal power pentode (Which cost around $2.50) by wiring a 5.1 ohm resistor between the pins of the filament and fabricating an octal-to-four pin adaptor.