There is no source of firm guidance, as there is for cars. You can check various RV FOR SALE web sites to see what others are asking for similar units. RV Trader is a big one. RV Life may have its own. There are others. Once you have found one similar to yours, compare its description to an honest description of yours. This will at least get you in the ball park. Some thoughts to help steer you include:
o Values peak in the spring, and sink as the end of the camping season approaches - kids go back to school, cold weather approaching, etc. The difference can be substantial. If your situation would allow you to wait for spring, you might benefit.
o Values on the west coast are consistently higher than values in the east. I don't know where Houston falls in the range, or if your TM is even located there, but probably higher values than in the snow belt.
o By far the most important factors are the TM model (and the 3124 is well-valued) and its age. What is the model year of your TM?
o Next is condition. To avoid simply wasting time, you need to be honest about the condition of your unit right from the start. Potential buyers will ask about many things, and problems will reduce the value, but less if you are up front about them. Items that are easily handled, like tires and battery, won't have an outsize effect. A history of water leaks can be a bigger deal, and a front roof that has lost its crown (the arch under the air conditioner) would be another.
At the top of the "TM FOR SALE" section of this Forum, there is a post about how to write a good ad. Start there, to avoid handicapping yourself when you write the ad. Then, a subsection of the same section is called the For Sale Archive. These are ads that have been posted and successfully sold. Some of them still show the asking price, so that may help you.
Good luck!
