First of all, your #1 tool for organizing is competition software. Check out "brew competition" It's free and easy to use. It's in the form on a website and people will be able to enter their beers, pay for entries, and register as a judge or steward. You will have a ton of advance information using this and know what to plan for.
If you plan on giving prizes to winning brewers, you should solicit breweries, homebrew shops and any beer or brewing related company. You'd be surprised how many are willing to donate. AHA will give you a nice donation if asked, after you've registered with them.
If you choose to use them, AHA medals can be bought for $2.50 or so each from The Hermann Werks (http://www.thewerks.net/) Keep in mind that you'll probably be combining categories so you wont need medals for all 23 categories.
BJCP will send you a list of all registered judges once youve registered. Email all of the judges from Mass and any neighboring states asking for them to attend. Send the link to the website so they can register. The number of judges you'll need depends on the number of entries. Usually in groups of 2, a group of judges can sample and judge 4 beers an hour. From there you can figure out what you need. Also, you'll need to feed the judges, keep that in your mind and budget.
Organizing all the entries is a HUGE ordeal. Give yourself enough time between the entry deadline and the competition to recieve all the entries, organize them and label them. It's also sometimes difficult to group small categories appropriately.
The BJCP has some awesome info for you on their site: http://www.bjcp.org/compcenter.php You can get all the forms/score sheets/flight summary sheets/cover sheets that you need there. Look into the Queued Judging as well, it's very helpful.
That was a mouthful. If you have any questions, feel free to ask.