Unlike many I don't necessarily recommend starting with a cheap detector. I say, buy the one that has all the modern electronic features you can afford. Even the most expensive detectors have a turn on and go mode that you can use until your are able to learn your detector. Besides, it is fun to experiment with different features on your new detector. You accomplish a lot more by doing than by just reading. Also, there are dozens of folks here on Tnet that will be able to give you most of the guidance you will need. Stay away from Chinese made brands that at first appear to be a real bargain. Stick with your well knowns such as Garrett, Whites, Bounty Hunter, Minelab, Fisher, etc. Sorry if I left anyone out.
Now if you think you would rather enter with a less expensive detector, by all means the Garrett ACE 250 is by far the most recommended starter detector. However, and most important, if you intend to hunt salt water beaches the ACE250 is not the way to go. You need a machine with an adjustable ground balance instead. Just remember the formula, salt water = adjustable ground balance and you won't get into trouble. In closing, read all you can on detectors before making a decision, check for individual member's evaluations here on the net and ask lots of questions. No question is stupid so don't hesitate. Monty