As far as I can tell there is no option to "buy out" an e model to remove the subscription requirement. Given HP's history I suspect once this annoys the wrong person it'll turn out to be pretty trivial to break, but for now if you feel the need to purchase a new HP product you should definitely avoid the ones with an e in the model number.
AFAIK Brother hasn't tried anything like this (yet?) and they're cheap so if they fit your needs I recommend them.