Missagonie,
my advice is - BUY A JUICER (I suppose u could afford the cheaperst one)! U can use it even ur fast is over :)
Ok, the aim of a juice fast should be not only to loose weight but also to supply ur body with healthy vitamins and minerals. Am I correct?.. Bottled juices are DEAD. Also in some of them there are some not very healthy 'additions' (even if u are determined to buy just the ones NOT from concentrate). Moreover u will feel constantly hungry by drinking not 'alive' juices. I can surely say it will be more difficult for u to stay on ur fast.
Buy a juicer. Drink as many juices as u want to. PPl here recommend 3-5 cups per day. Try to drink juices within 10 min after juicing. At least do it in the morning and/ or the evening. In between keep them in air tight containers (and in a fridge). Make sure u get rid of pulp in juices otherwise u can feel hunger for extended period of time if not all the time (use tea strainer with very small holes for it). Drink vegi and fruit juices separately (some ppl say it is ok to mix apple and carrot juice - possibly- I personally dont). Drink melon juice separately from other juices.
Also make sure u end ur fast properly otherwise u can gain ur weight back plus something extra... Drink fruit juices as well. Dont worry u still will have ur weight loss :)