What would be a good list of tools to get started?
Would you consider it a monetarily expensive hobby?
I live in St. Louis, Missouri. Any recommendations on easy and cheap first trees? I’m thinking a ficus for indoor.
If you’re really set on growing trees indoors,
Ficus microcarpa is a good option. As others have said, you’re better off growing trees native to your climate, keeping them outdoors year round. Look at the tree species growing around you and then check to see whether others have been successful training them as bonsai. When you nail down a local species considered easy for bonsai, head to the garden center and look for some healthy ones with thicker trunks. Now is not the best time of year to collect wild trees.
As for tools, you don’t need anything fancy to start. A small pruning saw, bypass garden cutters, and some wire will get you started. Eventually, you’ll want a quality pair of knob cutters to remove branch stubs when pruning. You’ll also want wound sealant for deciduous trees if you’re not leaving a stub from a cut branch. It mitigates water loss and prevents dieback.
As for containers, very early next spring, buy a wide, shallow nursery tray with a mesh bottom, prune the roots to fit in it, and plant the tree in a mix of pumice and finely-chopped orchid bark to start training the roots. Until then, keep your tree in the nursery pot and water thoroughly whenever the surface layer of soil feels dry. Let the pot almost dry out between waterings, but never let it get to the point of dryness.
You’ll find a lot more thorough information amongst the resources section of this site. Much of it will appear contradictory. Different people from different regions growing different trees are going to find that different variations on bonsai techniques work best. Identify someone who lives in a similar climate to yours and copy their methods.