As a Solitary Wiccan, why is it that any spell I want to do requires an expensive material?

Repent of your sins.

you dont need to buy expencive things. Most of those sites you get those spells/incantations from have a link to a shop which they own and so they make money. The basics are fine. Just bless them before you use them like you would anything you would use.
You can get most herbs from the supermarket and candles from there too.

Candles can be bought at the dollar store. Little ones go for like two for a dollar.
Most things you need can be bought at the dollar store. Need an athame? How’s a kitchen knife! Need a chalice? Plastic or paper cups! Wine? How about generic grape juice!
You just need to open your mind a little. If you’d like, you can list what items you’re talking about and I can give you their dollar store equivalents.
Also, as a note, you’re better off writing your own spells. They’ll work a lot better.

It doesn’t.
All that is required for a spell is mind and heart and skill (and I say this as a pagan supply store owner).
Candles, Incense, ritual tools, etc…etc…
Are just that…TOOLS.
Tools that help you communicate to your subconscious what it is you want from it.
Some of these tools (plant allies and such) can certainly lend their energies to the process, but there is no such thing as a “required” tool.

You’re not ready.
Wicca is a religion, not the practice of magic. If you are Wiccan, you should be focusing on the religion. Magic later.
If you think you need to find spells online, or need expensive items to cast spells, you’re not ready to practice magic. You have not put in enough study. You have not learned enough, or understood enough.
You’re just not ready for spells. My suggestion: back up and slow down.

You are meddling with forces you cannot possibly comprehend..

While this isn’t a specifically a Wiccan practice, I would suggest looking into sigil magic. Paper, pencil, visualization, and gnosis state.

You need more practice. Items that you use in a ritual are merely props that help you focus on what you’re wanting. Once you get better at focusing and controlling your energy, you won’t have to buy anything for a ritual to go well. I can’t remember the last time I bought anything for a ritual save maybe incense. Try using the strength of your mind, if you don’t have the cash or the resources to practice in the open.

Because you have no idea what your doing, anyone that is Wiccan, Pagan, witch ect knows that you don’t need to use expensive things, what you need is in your own house, your own yard or your own two hands….Read more and be honest with your parents, you live in their home you honor thier rules! Tis Respectful!