I was told that their computer was showing O2 sensor problems and that I was running "rich"

Are either of these anything to really worry about? If so, what kind of price am I looking at to get these problems fixed?

 

Sorry I didnt see this post sooner, it was at the bottom of the page.
You need a tune up, new spark plugs and plug wires.
When they wear out the truck runs rich because the spark is weak and the fuel is not burned completly and that unburnt fuel gets sent down the exhaust and puts the O2's out of range thus setting off the O2 codes and the running rich codes because ther is to much fuel being sent to the catalitic convertors.
Short term lower MPG, long term destroying your cats and excessive carbon build up on the exhaust valves.
www.atlanticbritish.com, any plugs you want and either Land Rover plug wires or better yet Magnecor (lifetime warrenty)plug wires.
You will also need a intake plenum gasket.

 

Before the tune up, give us the 4 digit fault code numbers, if you don't have them go get them read again, then and only then can someone actually give you some directions.
By the way, how many miles on the truck and has it ever been tuned?

 

81k...and I don't know if it has ever been tuned up, just got it a couple of days ago.

 

Assume that it has never been tuned up, get the Magnecor plug wires and new plugs.