I don’t follow. Speed and price can be many values, high or low. It’s perfectly valid to add an adjective describing it as fast or cheap.

Cheap means "low in price", so "cheap price" makes no sense.

Fast means "of a high speed", so it's the same here.

nit-nit, what's wrong with cheap prices? price doesnt infer magnitude.

Cheap means "low in price". Price can't be "low in price", it can be just "low".

Cheap has many more meanings than that. It can mean comparatively inexpensive (a cheap Lamborghini), of inferior quality (cheap paperclip), miserly (he's too cheap to buy better), gained with little effort (cheap win).

So what's a cheap price? A price of inferior quality? A miserly price? A price obtained with little effort? Or is after all a low price what's meant?

Sure. Still doesn't make "cheap price" a valid combo.

could be a contraction of cheap at the price https://en.m.wiktionary.org/wiki/cheap_at_the_price

That's a quality nit pick for sure.

J/k

It's a high quality nit pick imo:)

Somehow it has to be contrasted with ``slow'' speeds.

"High speeds"