You're probably not comparing apples to apples if there's that much price differential. You can get a 4-port wireless-N router for under 20EUR these days, though it'd be a cheaper Chinese brand with a less polished UI. Something like this would absolutely do the job, and I run TP-Link gear no problem, cheap and cheerful but not as idiot-proof as the established brands in terms of setup.
The primary price driver besides brand would be wireless capability. These days devices will come either with just the older wireless-N support, or with the newer wireless-AC standard. In the latter case they'll still have wireless-N as a fallback, it just means the device won't be operating at its maximum throughput. But that's not all, because there's a numerical rating attached to the standard, whether it be N or AC, e.g. N300 or AC1200. These numbers are a measure of their speed, but is not a direct representation of it.
Now for the N standard it's pretty simple. The number just means the theoretical maximum throughput, i.e. N300 is 300Mbps. You will never hit that theoretical value of course, but it's easy enough to compare various products with that figure.
The wireless-AC products though are misleadingly labelled because the number is the sum of two separate wireless bands that will be operating. When you operate an AC1350 router, you're not getting 1350Mbit, you're getting (theoretically of course) a 450Mbit wireless-N network operating concurrently with a 867Mbit wireless-AC network (and 1317 is rounded up to 1350 because reasons). This is why they are marketed as "dual-band". Modern devices will have the option to connect to the AC network and only get the 867Mbps or to the slower N network, you cannot connect the same device to both simultaneously. Older or cheaper devices such as game consoles would just connect to the wireless-N network and act as if the AC network wasn't there.
EDIT: The USB ports on routers are not designed for you to connect a PC to them, rather they are intended for things like printers or an external hard drive to share between the other devices connected to it.
Edited by Humanoid, 15 January 2017 - 08:06 AM.