אני לא רוצה לבזבז כסף על מונית אם אפשר ללכת ברגל.

Sometimes yes, but אני is very natural here.

The main reason is that רוצה in the present tense does not clearly show the person by itself. Depending on context, רוצה can mean I want, you want (masculine singular), or he wants. So adding אני makes it clearly I.

In casual speech, people do sometimes drop אני if the context is obvious.

In normal everyday writing without vowel marks, it stays spelled the same: רוצה.

But the pronunciation changes:

• male speaker: rotze
• female speaker: rotza

So a woman could write exactly the same sentence, but pronounce it differently.

Because the sentence is negating the main idea want:

• אני לא רוצה לבזבז... = I don’t want to waste...

If you moved the negation, you would change the meaning:

• אני רוצה לא לבזבז... = I want not to waste... / I want to avoid wasting...

That is possible, but it is a different structure and emphasis. The original sentence is the most straightforward way to say it.

That ל־ is part of the Hebrew infinitive, often corresponding to English to:

• לבזבז = to waste
• ללכת = to walk / to go

After words like רוצה (want) and אפשר (it’s possible / one can), Hebrew normally uses an infinitive:

• רוצה לבזבז = want to waste
• אפשר ללכת = it’s possible to walk

Not exactly. לבזבז means to waste, to squander, or to spend unnecessarily.

So:

• לבזבז כסף על מונית = to waste money on a taxi

If you wanted a more neutral idea of spend money, Hebrew often uses:

• להוציא כסף על... = to spend money on...

So לבזבז adds the idea that taking the taxi is unnecessary or not worth the money.

Because this phrase is about spending money on something:

• לבזבז כסף על מונית = to waste money on a taxi

The preposition על goes with the idea money on something.

If you were talking about the method of travel, then you would use ב־:

• לנסוע במונית = to travel by taxi
• להגיע במונית = to arrive by taxi

So על מונית is correct here because the sentence is about the expense, not the mode of transport itself.

Because the sentence means a taxi, not the taxi.

• מונית = a taxi
• המונית = the taxi

Here the speaker is talking generally about taking a taxi, not one specific taxi already known to both speakers.

Literally, it means something like if it is possible.

In Hebrew, אפשר is often used as an impersonal expression:

• אפשר = it is possible / one can

So:

• אם אפשר ללכת ברגל = if it’s possible to walk
• or more naturally in English, if we can walk / if one can walk

Hebrew does not need a subject like it here.

Because אם here means if, introducing a condition.

• אם = if
• האם = a marker for a yes/no question

So:

• אם אפשר ללכת ברגל = if it’s possible to walk

This is not a yes/no question, so האם would be wrong here.

Because ללכת can mean either to walk or more generally to go, depending on context.

Adding ברגל makes the meaning completely clear:

• ללכת ברגל = to go on foot / to walk

That is especially natural here because the sentence is contrasting walking with taking a taxi.

No—ברגל is the normal fixed expression.

Hebrew says:

• ללכת ברגל = to go on foot

Even though a person walks using two legs, the idiom uses the singular רגל.
Using ברגליים would sound much more literal, as if you were specifically talking about someone’s legs as body parts, not the usual travel expression.

Yes. That version is also correct.

The difference is mainly emphasis:

• אני לא רוצה לבזבז כסף על מונית אם אפשר ללכת ברגל.
  Starts with the speaker’s opinion: I don’t want to waste money...

• אם אפשר ללכת ברגל, אני לא רוצה לבזבז כסף על מונית.
  Starts with the condition: If it’s possible to walk...

Both are natural. The original just foregrounds the speaker’s attitude first.