Hey, i too just purchased an 04 Cardinal 31LE in great shape. I think i did okay on the price, just a little less than your price.
On thing you will want to watch are your tires! If you have Kenda Klever tires, get them off the unit as soon as you can! I have had two blow-outs in two weekend trips. Just returned from the second trip. Both failures occured in less than 30 miles from departing home. On the second trip (This past Friday evening) i checked tire pressures etc. All was good. Failure occured in about 25 miles,speeds never exceeded 55 mph.
I thought the first failure may have been due to low psi, apparently i was WRONG! Just Crappy tires! Take a look at the discussion in the technical section entitled Tire blow out or something like that.
I am trying to decide (since the first failure) what brand and model tire to replace all four with. Several people really dislike the Carlisle trailer tires, however my local tire dealer of whom i trust states he has sold a ton of them with no problems. The carlisle seems to be affordable, however, i dont want to continue to have failures. The failure this weekend caused damage to the unit. Really ticked me off!
In an effort to figure out the tire problem i had the trailer weighed. It weighs about 8600# dry, and mostly loaded, truck and trailer together weighs about 16500#.
One more thing, the Forest River owners manual for the 31 LE is really poor. If you need help drop me a note, i may have experienced your question.
Good luck and happy fulltiming!!