The calipers are a must, but an over-all-length gauge is fine, IF it has the cartridge that you are trying to load included. You do not need an expensive caliper. I have been using a cheapo for years. It does not have to be micro-exact. You need a press (you do not need to buy the fancy expensive crap), a powder dispenser, a balance scale (don't trust the electronic, unless it has a way to verify it), a case tumbler is fine, but you can clean the casings by hand, if they get real bad. Not important. A powder trickler is a must, to be able to trickle powder into your scale pan. There again, they are not expensive.
I really like Lee dies for the most part and they are not expensive. You can get whichever brand you want, though, as they are all good. Don't think that you need all expensive fancy stuff to get started. If you want to add dollars later, that is fine, but not necessary. Get Lee case trimmers for the calibers that you want to load for. You buy the cutter (cheap) and then you buy shell holders and pilots for each caliber (cheap). They are fantastic. I inherited an expensive Lyman trimmer and went back to the Lee. They are cheap and exact. I have used them for probably 40 (?) years. Get a case reamer tool, for using after you trim the casing (it reams inside and outside of the casing mouth)(cheap). Get one reloading book, just so that you have a hard copy of case dimensions. This is not ABSOLUTELY necessary, as most bullet/powder companies supply this data, but it is easy to go to a book to get it. You can get all of the load data, by researching online forums, and using powder company data. All companies give you data on line to get you started. You do not need a library full of reloading books, as they get outdated pretty fast, anyway. There are always new powders and bullets that are not included in the books.
One thing that you have to consider is, do you shoot enough to make the expense worth it? There is excellent factory ammo available now, that shoots great. If you just want another expensive hobby, then it is a great thing. I have been reloading for nearly 50 years and have hardly shot any factory ammo in that time. I got a press, powder trickler, and scale when I was 17. The scale was not great and I got rid of it, but I still use the press and powder trickler. It is the only one that I have. I added a good RCBS scale (gift from my fil) and a powder measure, which is another great item to have. I have paid for my equipment many times over, and it has allowed me to do LOTS of shooting.
The main thing to remember, if you decide to do this, is keep it simple. Don't let people feed you a bunch of bs about expensive stuff that you need. If you want to get into bench-rest shooting, then you can start splitting hairs. If you just want to have fun shooting targets, hunting, plinking etc., then you can keep it pretty simple using basic equipment.
I keep my process simple and have never had any issue finding loads that get me into 1/4-1 moa-better than my old eyes allow for the most part.
If you have any questions, I will always try to help you answer them, as I hate to have misinformation screwing someone up.
