... you know, you can go to Walmart and by a cheap temporary juicer for $50. That's what I did when I was first starting out. It'll work out to be cheaper than the packaged juices that way - I know those bottled juices are super pricey!!
I tend to disagree, there's no point in doing a fast if you're not using fresh juice. The packaged juice has been sitting for too long losing nutritional value (juice should be consumed withing 15 min. of being juiced or can be stored in an airtight container for a few hours max). Bottled juice been pasteurized and thusly has no enzymes. You might as a well be doing a water fast.
I'd just get the cheap juicer. it won't last forever like an expensive juicer, but it'll help you fast properly and you can accurately decide if juicing is a lifestyle you want to pursue and therefore invest in a better juicer in the future.