Field trip to Japan next June

JR pass covers the limusine bus from Narita to Tokyo? I have been working on this trip since this summer and got some estimates. Is it not reallistic for the group of 20 to go to Japan from US for $800~2100 per person? (7 nights) We are hoping to go to Tokyo, and maybe Kyoto. I would appreciate any input on this trip. Thank you!!!

Limousines aren't JR . they are private companies. JR operates trains to downtown Tokyo.
budget:
what do you include in your budget? flights? hotels, daily transportation, food and snacks?? what's the average age?/
I count 100 $ per day for a twin room in a busines hotel (budget hotel with private small bathroom and western beds) thought on the last trip, last month, I spent less.
I budget $ 40/ 50 for 3 meals a day, basic Japanese food all the way everyday plus the odd splurge of a huge ice cream parfait or expensive coffee and French pastry.
$ 10 a day for buses if can't use JR pass.
$ 10 a day for misceleaneous like entries to temples, whatever .
this comes to $ 170 per day. actually I pay hotels and "gifts" by credit card so I budget $ 100 cash per day and haven't spent that in any of 8 trips so far.
a suggestion: 20 people is a terribly unwieldly group in a country that is rather crowded and packed tight. many average restaurants , cafes, even small hotels, not to mention buses and trains will not accomodate your whole group together. if you haven't already planned to do it, split
in several groups each with a leader. You don't even all have to see the same things! some people will be bored by temples everyday, others by shopping everyday etc. If none of you has been to Japan, everything will be exciting, from stores window displays to the way they park cars in the smallest spots possible, to huge neons signs etc. so you don't all have to see the sites overcrowded by foreign tourists!

Is this a school trip?
Price depends on where you are departing from USA.
If you get your trip organized by the travel agency, you may be able to get a group rate at fairly reasonable price, there may even be a special deal for month of June.
I would say in order to travel comfortably and safely, you have to spend at least slightly under 2000 or more per person for flights and lodging (they may have a cheaper deal) but I doubt for 700.
Foods and land transportation may add up on top of that. But if you would check around on website, most of the tour (bus, mini bus etc)companies have group rates at reasonable prices.