Question is it a big deal to buy an used psu?

It's kinda hard to make out on Google translate, but basically the seller is selling a ATX case with two fans and a 700w PSU correct? This all for 4000 pesos (209 US dollars).

Can you verify what PSU model it is? Can you contact the buyer about the PSU condition? Does the website mercadolibre.com offer any grantee on your money back, if the item is described incorrectly or is damaged during/before shipping?