Yes, I think the Feynman lectures are worth the price. I have a copy that I purchased in a 3 volume binder (?), I think it was a commemorative edition. They were in a half price bookstore but they were shrink-wrapped and looked brand new, and possibly even un-opened for 85$. They are a bit sturderier than the paperback 3 volume set I inherited when a former graduate school roommate moved on. So you see, I bought them even after I had a thirty-five year old copy of them in paperback, so I thought they were worth the purchase.
Feynman lectures present physics in a novel, interesting manner. The lectures do not contain any problems to check understanding, but there is a separate volume that has problems. All told, for the majority of physics / engineering students, are better served with a conventional treatment from Resnick/Halliday, Knight, or Giancarlo. Feynman is a really good read after the conventional treatment, to appreciate what you already know, and to extend your knowlege. I have heard some physics graduates say they used the lectures in "brushing up" for their GRE's or even in studying for the less demanding part of their qualifying examinations, although most qualifying exam problems go beyond this level.
Depending on your goals, I can recommend them. If you want to read them for enjoyment, I can recommend them highly. If you are reading them for self-study to bring you up to the level of a third year undergraduate in physics / engineering, I think you will have to fill in some gaps.