Whooops...
I should have made that more clear.
If you're buying the machine outright, offer $50. If you're offering a trade, trade the Whirly for the Tag straight up.
If one of the used appliance places refurbishes and sells 12 series and older Maytags, you'll have to offer them more $$. Otherwise, $50 will be kind of an insult. For those places that just junk the old Maytags, $50 will seem very generous.