Not everyone can decide to freelance write and then go out and buy up a storm. Likely those are very few and far between. So, for most of us we are looking for ways to cut corners without leaving out something or making ourselves feel we are second rate.
First, consider what you really need versus what it would be nice to have. You can always get those nice extras later, like when you have a first real profit to show for your efforts, buy something slightly extravagant for yourself then. Meanwhile, make a list and cross off those things you can treat yourself to later.
I think the main essential in the computer age, is a computer, printer and matching software. But, don’t think you must invest thousands of dollars. Try thrift stores, ask family for copies of software and look online for freeware. Word processing software comes with new computers, likely you have a CD with MS Word or Lotus Notes. I use Lotus Notes myself.
Although we tend to back away slowly from computers and other hardware at thrift stores you should take a look, try plugging it in, booting up and seeing how it runs and what’s been left in it from the last owner. Printers and scanners are especially cheap (and plentiful) at GoodWill. Thrift stores aren’t likely to let you return a computer but you can test drive it before buying. Also, consider your needs, if you’re just using a computer for word processing and email you can manage without a new, souped up one for gamers and hefty music/ movie downloads. Check the software bins too, you may be amazed at what you find. Make sure software is compatible with your computer and check how old it is. Some software will have free updates online but that won’t help you if it’s too ancient to run on your computer to begin with.
Beyond the computer situation you need basic office supplies and reference books. These are often found at thrift stores, second hand bookstores, flea markets, garage sales, library cast offs, family and friends and office supply stores going out of business, back to school sales in the Fall, etc. Beyond the standard dictionary and thesaurus look for books about writing including grammar, word usage, style guides, editing and publishing. See if you can find general reference books for fact checking and research.
You won’t need a lot of pens and paper with a computer. But, consider having some kind of file system, a way to keep organized with story ideas, story submissions, publishing contacts, invoicing and whatever you use for self promotion and marketing. Find a system for keeping everything organized and work on maintaining it.