When you say precut are you just talking about the straight lines or a set of pre-bent lines just for your YJ? if you find pre-bent lines buy them, they fit like a glove. but for $150, I suspect you are just talking about the straight ones.
I find double flares to be a pain to get right, if you can do a good double flare then just buy the roll of tubing and do it yourself and save some money, I'm all about low budget. it won't be pretty but it will work! On the other hand if you have the money just buy the precut lines and get busy.