It does make sense. Consider the phrase "twice as cheap"
It probably means AWS is 440% more expensive.
Say “half the cost” or “cheaper by half”.
If the phrasing makes it clear they're talking about a higher price, then yes that's a good interpretation. You get half as good a deal.
Someone might say "half as cheap" to talk about a price drop by 50%, even though that's not really correct, but such is language.
Nobody says that. If someone said "once as expensive" I'd interpret "once" as talking about time.
"Once" can be a counter but not a multiple.