I’veSUGGESTION: Add a time marker. Indicate *when* you ordered the humidifier.¶
MY GUESS: Recently I ordered a humidifier.

(The original is possible, but vague. Adding a time marker maker makes it more natural.)

MY GUESS: I spent a lot of time on itsearching for the right one.

For the last 2 or 3 days, I was searching articles and reviews and reading them for 2 or 3 daysbout which humidifier to buy.

I couldn’t decidMoreover, I was unsure how much money I couldto spend on this thing.

Do I need a simple humidifierShould I buy a simple or an advanced onefeature-laden humidifier?

Is aAre humidifiers needed in the summer in [name of the country you live in]?

NOTE: Many readers do not know which country you are in. In Japan or Taiwan, humidifiers are probably are NOT needed. However, in the Middle-East or some parts of western China, maybe they are.

ALSO POSSIBLE: I am concerned that I willabout spending a lot of money and won’t use ifor a unnessary gadget.

I was afraid I would loseMY GUESS: Would it amount to a waste of money.?

SUGGESTION: Express this idea through a rhetorical question.

A new humidifier

I spent a lot of time on itdeciding on which one to buy.

Otherwise, "I spent a lot of time with it" it sounds like you repaired it or spent a lot of time assembling it

I was searchinghad been reading up on articles and reviews and reading them for 2 or 3 days.

I couldn’t decide on how much money I cshould spend on ithis thing.

IsDo I even need a humidifier needed inin the summer?

I was afraid I would loswaste money.

Again, I checked the level of humidity in my room —: 25%.

But I remembered last summer it was veryhow hot and humid it was in my room last summer.

But now I'm doubting if I made the right decision.

I am concerned that I will spendt a lot of money andbut won’t use it.

Changed to past tense so it fits with the rest of the writing