no telling bout the diff, they had some that were smaller that ran @$40, but i think they were too small to use....
he may have gottne the open fenders, there are two types, enclosed and open, the open ones are a good bit cheaper, i got a set of those for the front and i think they were around that price, $40 for the pair, but it also may depend on area, some areas are cheaper than others at the same store
I took some measurements and bought some 16G sheetmetal and made my own tubs for the back. As for the front I have one done but I took a 32X9 trailer fender from TSC and sectioned it to fit the front end. Worked out quite well, because this truck was hacked all to hell when I bought it.