Hi Finch, and welcome to airforums.com!
You'll find lots of good info on here to read while you are waiting for your dream AS to show up. Start reading all about it now, you'll be in a better place to judge any units you see.
I think you're looking in the right places, I found mine in a Kijiji not too far from me. But it took almost a year to find it!
One piece of advice: it's at least
$2k to replace all the appliances, and that's with you doing the labour, so other than frame rot, this is something I wouldn't ignore in a given trailer you look at.
So, if a trailer has some or all of them already replaced, check out what it would take for you to put them in, assuming you have all the technical expertise to do it yourself!
The three biggies are the refer (fridge), the water heater, and the furnace. The next ones are the water tanks, fresh, black and grey. These are all big $$ to re-do, so pay special attention to the state of the ones in any trailer you look at.
Chance are almost 100% that if the trailer is from the 1970s or earlier, all
the appliances need to be replaced. Newer than that, the per cent swings a little more in your favour, but not too quickly...
Anyways, good luck, and keep us informed. Be sure to send pictures of any you see, OK?