If you want to save money, and have the time, energy, and the desire to do so - maintain your yard yourself. Keep in mind that you'll get out of it what you put in. A great lawn takes routine aeration, dethatching, overseeding, fertilization, and water. You'll save a little money by doing all this yourself, however you'll likely need to purchase or rent some specialized equipment if you plan to do "all" of it yourself.
If you want to relax and the security of having a professional do it - then you might want to look into having a service come out and do it for you. Usually, you'll be receiving advertisements and special offers from lawn services around this time. See if you can compare a few local services to get the best price. Also, do a little research of your own on the internet or with a local nursery/landscaping company to understand what you "really" need, and what you don't. You won't be sold everything under the sun by a lawn care service this way.
A truly great lawn is a lot of work - it just depends on if you want to take on the challenge - or if you want to pay someone else to.
Hope that helps!