NuEra starts at 24'. The 21's are XCS (hard deck or cuddy-open) and XTSki (walk through open, cabforward). The Sebring is actually a 20.6. Though they made a 22.10 Sebring at one time I believe, and a 19 in the mid/late 80's.
21' K for an 11 year old boat sounds a bit high, but Lavey's do hold their value well. Might get better, more specific replies in the Outboat Section of Hot Boat.
RTJas
I consider the NuEra boats to be the new style hull when compared to my old school 21. The "Nu" boats are deeper "V" and sleeker styling. I have seen quite a few of the "Nu" style 21's for sale in the mid-$20k range. I think they started to build the Nu style hulls about 1996. I imagine the OB is a mod-VP hull which pre-dates the Nu style boats.