after our first two gliders we have picked up all the rest as rehomes/unwanted
off craigslist and other websites for low or no cost.
We found most sales are just people not wanting them anymore not really any
scams, although you have to be smart about it, and be watchful of a scam. And
most of what I would call a scam was just sellers wanting full price for older
gliders. so not really even scams, just to high a price.
Also the only time we had problems with introductions is when our colony of 6
had been together for a few years, the alpha male would no longer allow additions
even when the two had been with the 6 only 1.5 years before that time. the alpha
would only pick a fight, even after extensive scent training.
so you must always be prepared for the new glider NOT to be excepted. with smaller numbers of younger gliders my wife was always successful in introductions.