Oh my, that brings back memories. When I was in grad school, one of my fellow grad students was going to do a study using leopard geckos but they all turned out to be male and she decided to use a different species anyhow, and what with one thing and another she brought 'em back to the biology bldg to give away as pets. Several got loose. They did quite well for themselves, as the biology building was badly infested with a variety of cockroach species
, but most were caught within a few days. One, however, remained on the lam for IIRC about 3-4 months. Once or twice a week he would appear unexpectedly in the department secretary's office and go "GECKKK!" (you know, that noise they make when threatened) and leap off the wall at her and scare the bejeebers out of her. It was extremely funny, if you werent' her anyhow
I believe he was eventually caught.
Point being, if I actually have a point
, they can potentially survive quite some while in a building on their own if nothing eats or squishes them first, and judging by the biology department's experience, your best bet is to just keep an eagle eye out and hope to see him. I am not sure they
can really be baited in (although if your house is cold I suppose leaving a heatlamp on somewhere safe might be worth a try, and just look there frequently)
Good luck,
Pat