If we ignore the context, what is the meaning of 'phenomenal price?' Positive or negative?
How can you ignore the context, when you have an intensifier? Depending on the context, phenomenal can be either very positive or very negative.
Most frequently, it is used positively. For example, the tickets are offered at phenomenal prices.
In the following sentence, though, phenomenal means something bad:
It can thus avoid the forced choice of determinism or dualism, accounting for order and novelty without the heavy ontological price of a dualism or the unacceptable phenomenal price of the denial of order and novelty. (John Protev, Notes on Materialism) [Edit: This sentence was a totally wrong example. See the comment by Janus Bahs Jacquet.]
The program was established by the Canadian government to raise cash for the phenomenal expense of the war. / Two further sources influence the historical development of New Zealand masculinity: the Depressions of the 1880s and 190s, and the phenomenal price of the wars: Land Wars of the 1860s, the South African War, both World Wars and the Viet Nam War. / That said, one of the most common criticisms of Sony is the phenomenal price of the Sony Chargers and Sony power cables.
Phenomenal can mean either really low or really high.
So, "I don't agree with the question."
Phenomenal means "extremely impressive or surprising."
Sounds like a phenomenal endorsement to me.
I'd say that phenomenal is so overused nowadays and the phenomenality of prices is so ridiculously exaggerated that both within and without context it has negative connotation. To me it says "We'd like to emphasize the fact that we have the lowest prices possible. Our vocabulary is poor however, so we will call these prices… phenomenal".