2003 WSD, perhaps? https://archive.trekbikes.com/au/en/...900wsd/details

If it is the WSD (Women's Specific Design) model in 16" size, look for a sticker or decal on the seat tube to confirm.

Assuming it is, I'd play up that angle in your copy: Frames designed for women's proportions - longer legs & shorter reach primarily - that are more comfortable than frames designed around men's proportions.

MSRP new is $570. In my area, a 15 year old Trek 26" MTB with front suspension is ~$175-200 USD, fully tuned, cleaned, needed parts replaced & ready to go this time of year as the season starts to wind down. In a hot market and/or earlier in the season, maybe $250. As always, YMMV.