CAT5E Cable limitations

Does you main switch have a router attached to it? The only way I am aware of how to get more milage on cat 5 neworking is via router-router communication. We have a satelite site thats roughly 1500 meters away, they have their own private switch that plugs into a router, that router uses a modem to dial in to a router which we have here. By setting our router's ip address as the computer's gateway (from the satelite site end), internet access is granted to our satelite site as well as our primary site :)
I dont know what your situation is that requires a mini WAN, what do you need this solitary computer to do? If it just needs internet access, you can try just installing a phone line for it. Much cheaper than fiber optic lol.
IMO from the satelite site I can sign on to our internal network on our primary site, but due to the distance it is verrrrrrrry slow. I know the further the distance, the slower the connection. If you need this sole computer to be able to access your internal network, I dont know what else to suggest to you other than to get a few routers and try set up a mini satelite site for your situation.

Go wireless.
As for the distance limitation ,going over the spec in a wired network only slows down the network on that workstation.So instead of 100mb ,you might get 15 or 20mb.It will still work,just not as fast.

I agree with the answers about buying a cheap switch.

However as ther is only one pc that needs connecting you will probably be able to buy a 4 port hub cheaper.

This will work perfectly well.

I did a search on Google for ethernet extenders and got over 83,000 hits.

There are a lot of possible options for you. Blackbox as one said is a good source for hardware solutions.

You should have no problem finding a solution to your problem that don't cost an arm and a leg.

Good Luck Lee