К счастью, билет оказался дешевле, чем я ожидал.

К счастью means fortunately or luckily.

Grammatically, к normally takes the dative case, so счастье becomes счастью. In this expression, the literal sense is something like to happiness, but learners should treat к счастью as a fixed idiomatic phrase meaning fortunately.

Because к счастью is an introductory or parenthetical expression: it shows the speaker’s attitude toward the whole statement.

Russian usually separates such expressions with commas:

К счастью, билет оказался дешевле...

This works much like English Fortunately, the ticket turned out to be cheaper...

Билет is in the nominative singular.

It is the subject of the sentence — the thing that turned out to be cheaper. So the basic structure is:

билет оказался дешевле
= the ticket turned out to be cheaper

Here оказался means turned out to be or proved to be.

So:

• билет оказался дешевле = the ticket turned out to be cheaper
• билет был дешевле = the ticket was cheaper

The verb оказаться often suggests that the real situation became clear later, sometimes unexpectedly. In this sentence, that fits well because the actual price was different from what the speaker expected.

Because Russian past tense verbs agree with the subject in gender and number.

• билет is masculine singular
• so the past tense form is оказался

Compare:

• книга оказалась — the book turned out...
• письмо оказалось — the letter turned out...
• билеты оказались — the tickets turned out...

Because дешевле is the comparative form of дешёвый, meaning cheaper.

The sentence is making a comparison:

The ticket turned out to be cheaper than I expected.

So Russian uses the comparative:

• дешёвый = cheap
• дешевле = cheaper

After verbs like быть, стать, or оказаться, Russian often uses this comparative form directly:

• Он стал умнее. = He became smarter.
• Это оказалось проще. = This turned out to be easier.

That is just how this comparative is formed.

The dictionary form is дешёвый, but the comparative is дешевле. In other words, the stem changes a little when forming the comparative.

This is normal in Russian. Comparatives are not always formed in a perfectly predictable, mechanical way, so it is best to learn them as vocabulary items:

• дешёвый → дешевле
• дорогой → дороже
• хороший → лучше

Here чем means than.

It introduces the second part of the comparison:

дешевле, чем я ожидал
= cheaper than I expected

This is one of the most common uses of чем in Russian: after a comparative form like дешевле, лучше, больше, интереснее, and so on.

Because чем я ожидал is a comparative clause, and in Russian it is normally separated by a comma.

So the structure is:

дешевле, чем я ожидал

This is similar to English punctuation in a sentence like:

It was cheaper than I expected.

Russian is generally stricter about using the comma here.

Yes. In this sentence, ожидал can naturally correspond to English expected or had expected, depending on how you choose to translate it.

Russian does not have a separate past perfect form like English had expected. It often just uses the ordinary past tense, and the context shows the time relationship.

So:

чем я ожидал
literally = than I expected
but in natural English it may be better as than I had expected

Also, ожидал is imperfective, which fits the idea of an ongoing mental expectation rather than one single completed action.

Russian often leaves out words that are obvious from the context.

Here the full meaning is something like:

• cheaper than I expected it to be
• cheaper than I expected the ticket to be
• cheaper than I expected

The missing idea is understood from дешевле. English does something very similar, so this omission is quite natural in both languages.

Yes. Russian word order is flexible.

For example, you could also say:

Билет, к счастью, оказался дешевле, чем я ожидал.

That still means the same thing. The difference is mainly one of emphasis:

• К счастью, ... puts the speaker’s reaction first
• Билет ... puts the ticket first as the topic

The original sentence is very natural and emphasizes the fortunate result right away.