FIRST, find out exactly what that $200 is getting you. They have to tell you exactly what it is, you paid them, dont beat around the bush, its your $ and your truck and you have the right to know EXACTLY what they are doing!
Now, personally, Id never pay the dealership to do something, ever. Unless you have literally no tools and a place to do some work whatsoever, I wouldn't bother having any outside do this type of regular maintenance. IF for $200 they're doing all the fluids, plugs, air filter Id say its a good deal but Im sure this is for just plugs, probably hit you for $500 for all the other stuff, parts/labor aint cheap haha.
Fluids all together (2 diffs, trans and tcase as well as engine oil) will run you around $150 or so if you get a good deal on the 75w40 gear oil, crap is expensive! Like $25 a bottle and it takes about 2/diff (front & rear) The plugs are an easy swap, takes maybe 15-20 minutes at the most and cost $20-$30 for a nice set of aftermarket plugs. YOU DONT NEED OEM plugs, there is no difference and you would never notice the difference between oem and aftermarket. Dont let someone tell you otherwise. Not saying all plugs are made equal, but Champion, NGK, Bosch are all good names and would be the equivalent to OEM
Plugs are good for a long time, but if your at 47k on OEM ones, Id say its time for a change just cause they're not to expensive and if your making a project out of it all, Id say just do them and mark it off the list.
Engine oil is easy as well as you know and you can grab that at your local Napa. I too am not a huge believer in fancy oils. ITS MUCH MORE IMPORTANT to change your oil regularly at every 3k miles (although it will last much longer) than to change it every 4k or so or some irregular interval with "good stuff". People will try to sell you on royal purple or valvoline or mobil one all the time but in reality its differences are minute and insignificant if you change your oil regularly and take care of your car/engine in general
Synthetic is another story but regular oil is regular oil, or has been for every car Ive ever been around forever
The whole kit and kaboodle shouldn't take more than a few hours to do all fluids, plugs and maybe an air filter and you could even do the serp. while you're in there
Anyway, thats my thoughts on the whole "maintenance thing" Much more important to do things regularly as required by service manual than to use name brand stuff and not do it regularly. And much more important to LEARN how to do these and save yourself thousands in a lifetime in not having a third-party do it for you
G/L with the project.