An older one will be expensive too, because of all the repairs it will
need.

See
http://autos.groups.yahoo.com/group/VintageTravelTrailerRestoration/
for pictures and descriptions of work people have done to make a
cheaply-bought old trailer into a useful RV.

I bought a 1988 model exactly two years ago. When I bought it, it was
almost 100% functional. It needed tires and the water heater wouldn't
stay lit. Since then, besides the cost of stocking it with all the crap
I want while out living in it, I've bought loads of small $20 parts,
and some big ones -- and done lots of labor myself. I'm very handy,
very technical, and very physically able. If you don't mind me doing
some gender stereotyping, most women would neither be capable nor
willing to do most of the work I've done. I can't imagine how much it
would have cost to pay for the work.

It can only be worse for a model that's 15 years older. You're talking
about a 33 year old RV.

I didn't know they exist without bathrooms, but perhaps you'll want to
skip it just to save on costs and repairs. Just be sure to get sites
near the campground's bathrooms.

The RV should probably cost between 500 and 1500 dollars, depending on
condition and how much of it is new.

What will you be using to tow it?

Just as mentioned by others in your previous threads...It still does
not sound like a wise investment for a single mom on a short budget.