I think sergers are really underused because we just don't know enough about them. If you do other sewing besides quilting then you will use your serger. You would be surprised at what you can do with them. I think of my serger as an accessory, so if you can afford it - go for it!
You seaming is always nicer when your use your serger. For example if you made flannel pajama bottoms, you would only need your regular sewing machine for the waistline casing and the hems. And they stitch very fast!!
Its so nice to look at something you have made and see those nice finished seams.
There are some good serger books out there. Sewing with Nancy has had some shows and has books on serging as well. Find some books you like and then get them at the library. If your local library doesn't have them, try your statewide library system if you have one.
Janome makes a couple of reasonably priced models, starting at just $200. Hancock Fabrics sells a few models and are frequently on sale. There are even some out there that are self-threading.
I am glad I have mine and would purchase another one if I had to.