Please don't buy such stuff from AliExpress, everything there is fake...
where do you recommend me buying it? local store? or another online site?
alright, is there a brand you would recommend? and i read that some repeaters should always be linked to the modem via a LAN cable (hope i'm not saying bullshit right now) , and others not, how can you know? what should i look for when buying it?
ironman wrotePlease don't buy such stuff from AliExpress, everything there is fake...
Why do you say this?

Larsa,What router do you use?
Some routers offer bridging technology which is equivalent to repeating.
I have the D-Link black router Ogero gives out during installation
My current set up is one main tp-link router, and another secondary one on which i set up a bridged connection so it is granted internet access through the first router.
The point is, routers have the feature you need, often. So you might not need a repeater but just another router of the same type.
But i don't know if your router supports bridging.
Aliexpress will take weeks to arrive, just order this repeater from pcandparts TPLink TL-WA750RE 150Mbps Universal WiFi Range Extender $32.00.

It's super easy to setup, just push the wps button. I have one myself.
i assume latency is not a problem, and will not be used for online gaming.
as random-username said, this is the best option :)

Good luck.
17 days later
I don't recommend this item. I have it at my parent's place. The main problem is that TP link RE does not provide seamless wifi roaming despite using wds with the main tp link router.