**First solution - perfect match but expensive.**

Asus prepared solution which is perfect for your requirements but it's really expensive and it's over your budget. It's [ASUS CS-B][1]:

It meets your requirements:

Dual LAN: 

 - Intel® I217LM
 - Realtek® 8111G

USB Ports 

 - 2 x USB 3.0
 - 4 x USB 2.0

It's mATX.

But:

**Cost: $200 (Amazon US)** 
 


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**Second solution - better and cheaper** 

You should just use [@john kieran solution][2].


  [1]: https://www.asus.com/Motherboards/CSB/specifications/
  [2]: http://hardwarerecs.stackexchange.com/a/2067/1366