My advice for today for activism and/or any project operating on a budget is get creative with resource acquisition. My father grew up in poverty, so he taught me all the tricks of the scavenging trade. Knowing how to get more for less can be a powerful skill in pursuing large projects, so here's a few tips:
Think of thrift stores and second-hand places as a resource. When I was guerilla decorating the science department at my university, that's how I got all the throw blankets. I also thrift-shopped for the pants I used for the Emergency Lab Pants project.
If you have a Habitat for Humanity near you, they take opened cans of paints and stains (in addition to the second-hand furniture they're known for) and sell them for waaaay below market price (usually just a few dollars). If you want the option of buying more of the same paint later, be sure the barcode on the can is still legible and take a picture of it.
Lowe's usually has a mismix rack of paint near the paint department. These cans of paint are also only a few dollars, but they cannot be replicated. You should not bet on being able to get an exact match for more paint later.
Check the lots behind manufacturing facilities if you need construction supplies. Places that use wire often put large wooden spools near the trash, and anywhere that loads and unloads large numbers of items usually throws out pallets. You can use these as a source of free wood (they're kind of hard to get apart though), and the spools make good tables when you turn them on end. Safest bet is to actually ask someone if you can take stuff, but if it's all out near the dumpster, I usually take that to mean it's trash (and no one has ever yelled at me for taking materials this way).
If there's literally anything you need, but especially furniture, look up the graduation date for the nearest college, then drive the college neighborhoods during the last two weeks of classes. People put all kinds of stuff out on the curb - chairs, tables, shelving, watering cans, stools. One time I was building a vegetable garden, and I got two 11 x 2 foot raised beds from someone moving out of a rental property? The more expensive the tuition at the university, the more likely you are to get more stuff on the curb because just getting rid of stuff in time to end leases is more important to well-off college students than carefully reselling all their items. I once bought a big shelf off a college student for $15 (I was in college and had access to the buy and sell group chats), which I used to create a community library at my low-income apartment complex.
Join your local Buy Nothing group on Facebook. You can only join one, so join the one for the locality most relevant to you, but these groups were established as a movement for the giving away/trade of goods (almost any goods) for free.
If you just need cheap, check Facebook Marketplace and other similar sites (but BE CAREFUL if you're meeting up with someone to pick up the goods).
If you need access to any kind of resource, ask a local librarian. Some towns have things like "libraries of tools" where you can check out stuff like a nail gun so that you don't have to buy one (this is especially nice if you'll only need it for one project).
Never hurts to Google different kinds of swaps in your area. My area has relatively frequent clothes and plant swaps. Last plant swap I was at, lots of people brought stuff like strawberry and raspberry plants, so you might be able to get access to free perennial food crops.
Also never hurts to Google "[business name] coupon" and see what codes come up online on places like Coupon Chief, RetailMeNot, etc. If you need something from Michael's, that store has a standing 20% off coupon on their website that you can look up and scan at the store from your phone.
This stuff is especially helpful if you're trying to decorate and furnish some kind of community space, or just need some form of physical supply - ex: paint for community murals, shelves to make mini communal libraries/pantries, scrap wood to make fencing for a community garden, etc.
