"It's the last week of cheap prices."
Translation:Es la última semana de precios baratos.
It accepts 'precios bajos' as well. In English 'cheap prices' sounds wrong. An item is cheap, the price is low. Does this translate the same to Spanish? Does 'precios baratos' sound strange as well, or is it standard?
Always use "ser" when talking about the time things take place. Thinking of "temporary/permanent" is okay as a rule of thumb when deciding between ser/estar, but it can lead you astray. For example, the location of a building is pretty permanent but because it's location we use "estar" for it.
That's a good question. The nearest I can get to guessing is that 'ser' is used for time and dates, which could include 'It is the last week...'
Nor was 'la semana última', so it seems to require the adjective to come first. Does anyone know whether it's required here for the adjective to come first, and if so, why?
Limiting adjectives (adjetivos determinativos) are normally are placed in front of the noun. These include adjectives which indicate quantity [e.g., mucho(s), poco(s), cuanto(s), todo(s), dos, etc.], articles (el, la, un, una, etc.), unstressed possessives (mi, tu, su, etc.), demonstratives (este, ese, aquel, etc.), and moral qualifiers (buen, mal, etc. if not preceded by adverbial modifiers such as muy) and particularly the comparative/ superlative forms such as mejor, peor):
As far as I know anything to do with the amount or similar of something goes before the noun.
So three weeks, or many weeks, or the second week, or the next week...etc would all go before.