Multiple RC522 connecting to a PC

Imagine you have 18 objects with RFID tags on it - each tag carries information of what the object is. Now, there are 18 RFID reading stations (RC522) and each RFID tagged object also sits on each station. These stations are not that far from each other and are pretty much on the same table.

Each RFID station will report of the RFID tagged object whenever it enters or leaves its station. An RFID tagged object could be swapped with another RFID tagged object on another station, and they will just report the new corresponding RFID tagged object upon entering the station.

All of these are connected to a PC that is connected to a HDMI monitor and display information of any entering/leaving of the RFID tagged objects.

In this setting, the following technical possibilities are discussed:

A. Use several arduinos and connect several RFID readers to an arduino as many as possible, and connect each arduino to a USB port. On the PC, there will be several nodejs taking care of each serial inputs of each arduino. This setup requires the computer to have multiple USB ports.

B. Another alternative I could think of is perhaps use an Arduino that has LAN port and connect all Arduino into a LAN Switch along with the desktop computer. This might be more ideal, but the code of the Arduino will no longer be sending data via Serial USB, but via LAN instead, perhaps using something like websocket. (So the desktop could also communicate back to each Arduino if required)

If it is you, do you think B is the appropriate choice in this case? I see Arduino Yún Rev 2 | Arduino Official Store, but is there a cheaper model with LAN port? $59 is a bit too much for me, especially when I need a few of these.

Or is there a cheaper or better alternative in this case? Any help would be appreciated.

You can connect as many modules to the Arduino as you have free digital output pins for the Slave Select lines. More if you use decoders to e.g. activate 1 of 16 SPI device from a 4 bit code.

For PC communication a single channel (USB, Ethernet...) is sufficient, it's your PC code that distinguishes and handles the reported tags.

If you do want to use Ethernet, there's no need to mess with the Yun. Just use a regular board with an Ethernet shield or W5x00 module connected. You can get Ethernet shields in the classic form factor or in the MKR form factor.