It all depends on the price and condition of the buggy. The 777 while being a good kit has been replaced by the MP9. The X1 has also been replaced by the X2. While as a new racer to this scale, you may not be able to tell the difference right away but it would really suck if you needed to buy certain parts later that could be discontinued. For the most part, I doubt they will discontinue parts for either buggy for atleast a year or so. Both are very popular, and most of the drive train components from the older vehicles can be replaced with parts from the newer ones.

What's your price range you feel comfortable with? Also, have you raced anything fuel powered? Do you have experience tuning a nitro motor?

You'd need a good starter box, I recommend the ofna 12 volt motor chrome top. It's pretty reasonable, and last a long time. I've had mines for over 5 years without any problems. You'd also need your radio, and something with 2.4ghz is recommended.