It must work with only the components nessasary to cast it.

<spell>alarm</spell> needs wire and a bell. I can set up an alarm using it

<spell>animal friendship</spell> needs a bit of food. I can easily make an animal think I am nice by feeding it

With a few exceptions (plane shift's tuning fork, for example) almost all spell components can be obtained in real life - they're just a lot more expensive.

I decided to go through the 2024 PHB and check the material components for all spells.

Out of 391 spells listed in the book there are 2 spells you cannot get the material components for in real life.

Flesh to Stone
A cockatrice feather
No such thing as a cockatrice in real life, it's a mythological creature, so this one cannot be obtained.

Plane Shift
a forked, metal rod worth 250+ GP and attuned to a plane of existence
While certainly possible to get a metal rod of precious metal and adorned with gems or something to get the value it's the "attuned to a plane of existence" part that makes this impossible to get, since such a thing is impossible in reality.

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In general most things are just a case of getting something commissioned made out of the needed material and decorated with expensive metals and jewels. Several things call for "powdered" diamonds, metal, etc. While some are uncommon, all are available to buy. Powered silver and, surprisingly, powdered diamond are actually very common. Powered diamond, in particular because it has industrial uses, powdered silver is also used for making ionised silver for use in home remedies and the rest are common for expensive decorative projects. 

Most things are just a case of "getting enough for the value". 

Some require a reliquary which is a container intended to contain a sacred relic. You can easily commission one or buy one. 

Here are some you might think are unavailable to get but actually are:

Protection from Evil and Good
A Flask of Holy Water worth 25+ GP
This would be about $2,000 to $3,000. Holy water is easy to come by, and some churches might let you get some free. So the cost is mostly the flask itself and while difficult you could find somebody to commission a very extravant flask made with diamonds and precious metals. People have made far weirder things.

True Seeing
Mushroom powder worth 25+ GP
This is around $2000 to $3000 USD. It might seem like how can you get a mushroom this expensive? Well, actually, yes there are mushrooms this expensive. White truffle is a mushroom that sells for over $4000 per pound.

Witch Bolt
A twig struck by lightning
It would normally seem like this should be difficult. However, it's not. There's stores that specifically sell this kind of thing for decorative purposes. They check reports for lightning storms in woods and beaches and then after go there to collect struck wood (the lightning leaves interesting details in the wood) and sand (it creates unusual glass sculptures) - in fact the sand one was actually referenced in a movie (Sweet Home Alabama) where a character did this as a hobby and eventually opened their own store. People actually do this in real life.

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So yeah, if you have enough money nearly all the material components can be obtained in real life.