אני לא מרשה לעצמי לקנות משהו יקר סתם כי אני עייפה או עצבנית.

Literally, it is something like I do not allow to myself. In natural English, that becomes I don't allow myself.

Hebrew often expresses allow oneself to do something with:

להרשות לעצמי + infinitive

So:

אני לא מרשה לעצמי לקנות...
= I don't allow myself to buy...

This is a very common pattern.

לי means to me, but לעצמי means to myself.

In this sentence, the idea is reflexive: the speaker is both the person making the rule and the person affected by it. Hebrew normally uses להרשות לעצמי / לעצמו / לעצמה for allow myself / himself / herself.

So:

• אני מרשה לעצמי = I allow myself
• הוא מרשה לעצמו = he allows himself
• היא מרשה לעצמה = she allows herself

Using only לי would not sound natural for this meaning.

Because Hebrew usually follows verbs like allow, want, can, start, and similar verbs with an infinitive.

So the structure is:

מרשה לעצמי + לקנות
= allow myself + to buy

The ל- at the start of לקנות is the normal marker of the infinitive, like to buy in English.

Because את is used only before a definite direct object.

משהו יקר means something expensive, which is indefinite, so there is no את.

Compare:

• לקנות משהו יקר = to buy something expensive
• לקנות את הספר היקר = to buy the expensive book

In the second example, הספר היקר is definite, so את is required.

Because in Hebrew, adjectives normally come after the noun or pronoun they describe.

So:

• משהו יקר = something expensive
• בית גדול = a big house
• רעיון טוב = a good idea

This is the normal Hebrew word order.

Because משהו behaves grammatically like a masculine singular word, so the adjective agrees with it.

That is why you get:

משהו יקר

and not:

משהו יקרה

So even though something feels vague in English, Hebrew still gives it grammatical agreement.

In Hebrew, אני means I for both men and women. The gender becomes clear from other words in the sentence.

Here, the clue is:

• עייפה
• עצבנית

Both are feminine singular forms, so the speaker is female.

If a male speaker said it, it would be:

• עייף
• עצבני

Because in everyday Hebrew spelling, some present-tense masculine and feminine singular forms are written the same way.

So מרשה can appear with either a male or female subject in unpointed Hebrew. In this sentence, the feminine adjectives later in the sentence tell you that the speaker is female.

This is very common in modern Hebrew: sometimes the written form does not make gender obvious until later.

Here סתם means something like:

• just
• for no real reason
• for no good reason
• on a whim

So it adds the idea that the reason is not a good enough reason to make an expensive purchase.

It is not just a neutral because. It has a dismissive nuance.

Because they do different jobs.

• כי = because
• סתם adds the nuance of just / merely / for no good reason

So:

סתם כי אני עייפה או עצבנית
means something like:

just because I'm tired or irritable/nervous
or
simply because I'm tired or irritable/nervous

Together, they give the strong sense that this is a bad basis for buying something expensive.

In everyday Hebrew, עצבנית often means:

• nervous
• tense
• on edge
• irritable
• cranky

It does not usually mean sad. It comes from a different idea than English upset.

In this sentence, the most natural nuance is probably irritable / on edge / tense. The speaker means she should not make expensive purchases when she is in a bad temporary emotional state.

Because Hebrew present tense is often used for:

• habits
• general rules
• repeated behavior
• personal principles

So this sentence does not have to mean only right now. It can mean:

As a rule, I don't let myself buy something expensive just because I'm tired or irritable.

If the speaker meant one specific future situation, Hebrew might use a future form instead.

Hebrew negates the present tense with לא placed before the verb:

• אני מרשה = I allow
• אני לא מרשה = I do not allow / I don't allow

Unlike English, Hebrew does not need a helping verb like do. So there is no equivalent of I do not allow as a separate grammatical structure. Hebrew simply uses לא + verb.