Twin, does that auction come with a nitro starter kit? if not, you may want to go through www.ehobbies.com they are selling the MT2 for 280 and the nitro starter set for abouth 30, and as eville pointed out they have free shipping. As far as issues, Spare diff cups are a good idea. Also, loktite anything metal to metal that you take apart. That way you do not lose screws or break anything. Trust me on this, I killed a spur gear because of it. The radio is not a big concern any more, I talked to Cen and they said that they have corrected the problem with the radio. If you do have radio problems, call Cen and they will take care of the radio and any broken parts as a result of the radio failure. Anyway, a shopping list:

Diff Cups
Spur gear (at least a 47t for first)
spare screw set
glow plug
clutch shoes and spring

All of that is pretty much on an "as affordable" basis. As you drive it, you will learn what wears faster or breaks more on your truck. I would also advise using Cen clutch shoes or ones that are very similar in shape. If you have any other questions let me know.