Lets say I decided on the Lee precision breech lock challenger kit. What else is needed besides brass, bullets, primers and powder.
A couple of :
Universal-Ammo-Loading-Tray
https://www.amazon.com/MTM-Universa...eywords=+Reloading+-+Universal+Reloading+Tray
lee .44 magnum dies
https://www.amazon.com/Lee-Precisio...470882948&sr=8-1&keywords=lee+.44+magnum+dies
I'm not sure if you're going to trim your cases, I seldom trim mine - only when the casings are out of spec'.
In case you are going to:
Lee quick trim:
http://www.titanreloading.com/case-conditioning-tools
With its appropriate trimming die:
https://www.amazon.com/Lee-Precision-Quick-Trim-Die/dp/B00G3G851G
Scale:
https://www.amazon.com/Frankford-Ar...83764&sr=1-1&keywords=frankford+arsenal+scale
The press will do your priming, I do not use a separate priming tool.
I also don't use a priming tray, but if you must:
https://www.amazon.com/RCBS-09480-Primer-Tray-2/dp/B000N8HW3M
A set of Powder measure kit: (The die set will arrive with the dipper you're probably going to need, unless you charge a specialty round for that caliber). Just in case here it is:
https://www.amazon.com/Lee-Precisio...883396&sr=1-1&keywords=Lee+powder+measure+kit
Here's a more automated method for powder measure, Lee has some cheaper models that do the same trick, I like the RCBS one though.
https://www.amazon.com/RCBS-9010-Un...470883456&sr=1-1&keywords=RCBS+powder+measure
If you're going the manual way, you're going to need a funnel:
https://www.amazon.com/Lee-LP90190-...TF8&qid=1470884264&sr=1-1&keywords=Lee+funnel
If you're only doing one caliber at this point, you can get away just fine without a manual. Plenty of resources online for recipes.
I'll add that reading the Lyman introduction section with its process explanation helped me quite a bit. I wouldn't skimp and get it, or any other reputable manual. (There's a hard cover for this edition, this is not it, cheaper.)
https://www.amazon.com/Lyman-49th-E...eywords=lyman+49th+edition+reloading+handbook
Case lube would not hurt, you'll need it one day.
https://www.amazon.com/Lee-Precisio...&qid=1470884082&sr=1-1&keywords=Lee+case+lube
If I'm not mistaken, this should not leave you with any "Duh, I forgot to buy..." before you reload your first batch.
You may need a couple more items, but they can wait for batch #2, or maybe even #5:
A tumbler for example.
I tumble mine in a 5Gal bucket with dish soap, give'm a rub, water the neighbor's plants with the water (not really), and dry them in the sun.
If something pops in my head - I'll update this list under this line.