I bought my home for $245,000 and put about $15,000 into it…
If I could sell right now for $255,000-$260,000, and just lose money in interest and closing costs, would it worth it for me since I could talk a builder / seller down pretty good right now on another house….
Since it is a buyer's market, I lose money selling but make it up where I buy? What's the downside to this? Plus better mortgage rates….

Why are you wanting to sell?

Is it just because you think you can get a better deal elsewhere and you think you can pull some slick financial move? If so - sounds risky and not likely to pay off.

Now, if you have some crazy mortgage that is resetting and you can't afford it and are facing foreclosure - then selling quick and cheap is probably something to look at.

You purchased your house for 245,000 have put 15,000 into it = so you have 260,000 in your house. If you sold now for 255,000 you would lose 5,000 Plus 15,3000 commission (6%) Plus additional closing costs on the old home. Since it's a buyers market - there is a good chance the buyer will want you to contribute some to their closing costs.

Then you are going to incur commission and some closing costs on the new home. You would have to purchase the new house for 40,000 below value just to break even.

Unless you have a reason to sell - I'd stay where you are. It will take a few years, but the housing market will rebound. It probably will not go back to the all time highs - but will stabilize.