If you're going to use a mortar & pestle, invest in one that is stone/metal. Wooden ones are more common and accessible, but they're kinda shit from my experience. They don't last as long, they're not nearly as strong (seriously, the one's I've used couldn't pulverize fucking dried rosemary, c'mon), the wood can splinter off and contaminate your product(s), and then there's bacterial issues if the wood isn't properly sealed, which can also be an issue if the sealant/protectant begins chipping into your product.
Make sure you're actually going to use something more than once before you buy it. Do you really need that cauldron, or can you use a metal pot instead? Do you really need those crystals, or can you enchant a stone or something else to serve their purpose(s)? Do you need a fancy wand or can you use a twig or a pencil? Money doesn't grow on trees, but apples do. Are you buying something to use or to have? To be a tool or a decoration? (No hate if you want it for aesthetics)
Try to use old kitchen spices for witchcraft. Use newer spices/herbs for cooking; you'll get more of the flavor. Before you go shopping for an ingredient for magic, look in your pantry/spice rack. Use what you already have there, especially if they're older. Get newer spices to cook with. And don't be afraid to split ingredients between cooking and crafting; it's literally fine. Watch out for cross-contamination and you'll be ok.
Fabric is more useful for pouches that will be kept in the pocket, tight spaces, or traveled with. Bottles/jars are more useful for workings that will remain stationary, or those that contain liquid elements. Tiny charm jewelry bottles can work well for subtle/hidden magic. Use peat pods (decompostable flower pots) for workings that are to be buried. Do not throw workings into lakes, ponds, rivers, streams, or the ocean; that's littering and is damaging to the local ecology.
If you don't have space (or items) for a physical altar, digital altars are limitless. Make one in ms paint or photoshop; make a tumblr blog or pinterest board; make an altar in minecraft, animal crossing, dreamlight valley, skyrim, or whatever. Some might say it's cringe, but it saves space and gives you more freedom with design and items without costing much money.
Don't make a travel altar if you're not going to travel. Trust me. It'll sit in your closet or your desk or under your bed and just never get used. The water will dry up, the salt will clump, and the oils in the incense will end up eating through other things. If you don't need it, don't waste time and resources making one. You can plan them and design them all you want though, it's fun. But take it from someone who's done it more times than they should: they're useless if you're not actually going anywhere. (I plan to make a post(s) all about this when my spoons allow it)