My serger is as indespensable to me as my sewing machine is. You won't believe you were able to live without a serger once you actually have one and know how to use it. I have a 17 year old New Home (now Janome) 4-thread with differential feed (useful for knits) and only had it in the shop once because of operator (that would be me) error LOL!
If you do not know how to use a serger, they can be tricky at first. You will really need some training, either in person (sewing shop or other classroom/tutor environment) or with a beginner's DVD/video. My recommendation is to find a sewing machine shop within a reasonable distance to you that sells reconditioned trade-ins that will guarantee their work, and provide service and lessons. You don't need a top of the line machine, so an older reconditoned machine will be fine.
The previous poster makes a good point about machine needles. You'll want to check what kind your serger takes. My serger (17 years old) requires a special size needle, but many of the newer models take regular sewing machine needles. The special needles are not sold at the large fabric stores, and my original sewing machine store closed several years ago, so I order them on-line now and keep a supply on-hand. It's just something else to be aware of.
Also, make sure you follow the manual for care and upkeep (mine needs regular oiling), clean it after every use, and use good quality thread (I use maxi-lock).
Best of luck to you!!