Clair,
I, too, was curious about a serger a couple of years ago. I had a couple of friends who use theirs all the time.
So, I bought a new Singer 4 thread machine for less than $200. at WalMart.
I learned how to thread it one my own, then took a class that showed different uses.
I used it fairly often, and enjoyed it. Then, I went to the Houston Quilt Show last November and stopped by the Babylock booth to see what was new. Big mistake! lol
They had a show special on the Imagine, a four-thread, self-threading machine that is a real beauty. (And they were offering 2 years interest free.) The rest is history.
I sold my Singer for $100.00. and I love, love, love my new machine. As a test, I used it to piece a Turning Twenty for my DD. It worked great, an accurate 1/4 inch, and is really fast.
I won't use it much for other piecing, but I use it for lots of other things.
Bottome line, like others have said, start out on the cheap to see if you'll use it. Then, if you like, trade up.
Have fun.