What type of internet are you using? Is it some form of ADSL, fibre, cable or something else? This will affect what form of device you need.
Someone on eBay might be selling something older which does not have any wireless and that might keep the price low as most people go for wireless devices. If you need an ADSL2+ router then one could probably be found for very little if it can only be used wired.
Looking on our ebay and there are no wired routers but quite a few used wireless routers for fairly low prices.
Can you not just disable your wireless on the one that you currently have and attach via an ethernet cable?