i posted this a year or so ago but i thought i may be of some use to you.
a few suggestions for tea, to buy or to drink:
Teramachi Shijo agaru
Nakagyo-ku Kyoto Japan
Tel 81 +75- 221-1215
Fax 81 +75- 213-2502
*He is closed on a particular Sunday each month (second Sunday I think)http://www.fukujuen-kyotohonten.com/english/floor.html
Shijo Tominokoji, Shimogyo-ku, Kyoto-city, Kyoto 600-8005 Japan
Closed: on January 1st, Every 3rd Wednesday except November
Marukyu-Koyamaen Uji * a personal favorite, located in uji also.
Nishinotoin Tea House Kyotohttp://www.marukyu-koyamaen.co.jp
(near Nijo castle)
one piece of advice. Kyoto is a large busy city and travel time by bus or on foot can take up lots of your visit. if you don't travel by taxi or in a tour or private car, you should try to plan as best in advance. it takes away the spontaneity but in Kyoto with so much to do i found it more rewarding.
in tokyo there is a small nice shop for tea ware that i always enjoyed as i was just left alone to spend as much time looking at the two floors - even the flight up of stairs has tea ware on small side shelves - as i liked. although in asakusa, just down the street on a corner (look for the outdoor display), a few blocks from the kaminarimon gate on kaminarimon dori, it isn't a tourist shop. prices vary from affordable to very expensive.
my advice would be if you're not planning to collect an important work or from a famous potter, just buy what really moves you. because the high priced pieces can be so unobtainable it doesn't mean a 2000 yen piece won't move you and give you happiness to for years to come. and any shop carrying hand made items will certainly have beautiful pieces.
good luck and enjoy!
enjoy your trip.