..........................Trade-In.......Private Party............Retail
Base Price...........$19,210.........$20,593................$21,637
Mileage Adjustment
45,000 miles......$-1,816..........$-1,816.................$-1,816
Total...................$15,649.........$16,942...............$17,948
I got this from Edmunds, if you have any special equipment such as a trailer hitch, you shoud add that in. I used my zip code and your's will be slightly different. If you trade it in, you should expect $15,650 and if you try to sell it, it should be around $17,000. As you can see, having 45,000 takes about $1,800 off of your vehicle. I would use this as a guide. See what is selling in your area may be a good indicator.
http://www.edmunds.com/apps/usedmatrix/UsedMatrix