I would suggest you look at the Pro9 gear at
http://www.pronine.com. IMO it is a great value for the money (Chest protector is 1/3 cost of Honigs K-1 and is a slightly lighter knockoff version). Chest protector will work for the ages you are going to work (some say it is not good for high school age but I disagree). One of our association umpires uses the hockey style mask for college ball so it must be ok.
Prices are $45 chest protector, $60 shin guards, $60 Hockey Style mask. Prices are from Western Athletic Supply.
As others said - make sure you like the umpiring gig before spending a ton of money. ProNine is a good choice to accomplish this if you ask me.