Trypticon is a G1 figure, there is also Beast Wars II Gigastorm which are the only two of that mould in that size. There are no full size KO's (that I know of)
G1 Trypticon has become somewhat of an expensive figure on the secondary market, complete goes for $450 and upwards, however, incomplete the price can be as low as $150 but not in too good condition, sometimes he comes up in lots with his other big TF buddies and the price may go a bit lower as an average in the lot but you get killed in postage.
Your best bet is from overseas sellers as not many come up on Oz e-bay, I think there was one recently on Gumtree and was quite a good price with the box.
Battery covers and accessories on the big items are commonly missing because kids didn't care about them in the 80's :p:D Plus overall for a child it doesnt affect the playablity of the toy.