kono zyamu ha takasou ni miemasu ga, eki mae no suupaa de yasuku kaimasita.

高そう means looks expensive or seems expensive.

It comes from the adjective 高い (expensive / high) plus そう, which is used to express appearance based on what something seems like.

• 高い = it is expensive
• 高そう = it looks expensive

So the speaker is not directly stating that the jam actually is expensive. They are saying it gives that impression.

With い-adjectives, you remove the final い and add そう:

• 高い → 高そう
• おいしい → おいしそう
• 安い → 安そう

So 高いそう is not the normal form for this pattern.

Be careful: there is also another そう meaning I heard that..., but that is a different grammar pattern.

• 高そう = looks expensive
• 高いそうです = I heard it is expensive

The に is used because 見えます is a verb, and 高そう is being used adverbially to describe how something appears.

Pattern:

• [adjective/appearance form] + に + 見える / 見えます

So:

• 高そうに見えます = it looks expensive
• おいしそうに見えます = it looks delicious
• 元気そうに見えます = he/she looks energetic

Think of に here as turning 高そう into something like expensively-looking before 見えます.

Both can often be translated similarly, but there is a nuance.

• 高そうです = it seems expensive
• 高そうに見えます = it looks expensive

見えます emphasizes visual appearance more directly. It is especially natural when the judgment comes from how something looks.

So in this sentence, the speaker is focusing on the jam’s appearance: it gives the impression of being expensive.

は marks このジャム as the topic of the sentence.

• このジャムは = as for this jam...

The rest of the sentence then tells us two things about that jam:

1. it looks expensive
2. it was bought cheaply at a supermarket in front of the station

Using は is very natural when introducing the thing you are talking about.

No, this が is not the subject marker. Here, が means something like:

• but
• although

So the sentence has a contrast:

• It looks expensive, but
• I bought it cheaply at the supermarket in front of the station.

This is a very common use of が in the middle of a sentence.

駅前 means in front of the station or the area in front of the station.

Breakdown:

• 駅 = station
• 前 = front / before
• 駅前 = in front of the station
• 駅前のスーパー = the supermarket in front of the station

The の connects 駅前 to スーパー, so it works like:

• station-front supermarket
• more naturally: the supermarket near/in front of the station

Here, で marks the place where the action happened.

• スーパーで買いました = bought it at the supermarket

This is the standard particle for the location of an action.

Compare:

• スーパーで買いました = bought it at the supermarket
• スーパーにあります = it is in/at the supermarket

So で is used because 買いました is an action.

Because 安い is an い-adjective, and when you use it to modify a verb, it changes to the -く form.

• 安い = cheap
• 安く = cheaply

So:

• 安く買いました = bought it cheaply / bought it for cheap

This is the adverbial form of the adjective.

Other examples:

• 早い → 早く = quickly / early
• おそい → おそく = slowly / late

The subject is omitted because Japanese often leaves out information that is understood from context.

Since the verb is 買いました (bought), the listener usually understands that the speaker means:

• I bought it

So the full idea is something like:

• I bought it cheaply at the supermarket in front of the station

Japanese often omits 私 when it is obvious.

Because Japanese often omits objects when they are already clear from context.

The topic このジャムは is introduced at the beginning, and then the sentence continues talking about the same jam. So repeating it would usually be unnecessary.

A fuller version could be:

• このジャムは高そうに見えますが、駅前のスーパーで安く買いました。

The omitted object of 買いました is understood to be this jam.

Historically and literally, 見える relates to be visible / appear, but in this sentence it is best understood as looks.

So:

• 高そうに見えます = it looks expensive

It does not mean that someone intentionally sees it. It describes how it appears to the eye.

The sentence uses polite ます style:

• 見えます
• 買いました

This is the standard polite style used in many textbooks and everyday conversation when speaking politely.

The plain-style versions would be:

• 高そうに見えるが、駅前のスーパーで安く買った。

Both are correct; the difference is mainly politeness and tone.