ano mise ha takasou desu ga, zissai ha sorehodo takaku arimasen.

高そう means looks expensive or seems expensive.

It comes from the adjective 高い = expensive / high, plus そう, which expresses appearance based on what something seems like.

So:

• 高い = is expensive
• 高そう = looks expensive

In this sentence, the speaker is saying that the store gives the impression of being expensive.

These are two different grammar patterns:

• 高そう = looks/seems expensive
• 高いそう = I hear that it is expensive

So:

• そう attached directly to the adjective stem shows appearance
• そう after the plain form shows hearsay

With 高い, the appearance form is made by removing い:

• 高い → 高そう

That is why this sentence uses 高そう. The speaker is judging by appearance, not reporting information they heard.

は marks 店 as the topic of the sentence.

So あの店は means:

• as for that store
• that store, ...

The sentence is talking about that store and then making two comments about it:

1. it looks expensive
2. but actually it is not that expensive

Using は is very natural when introducing the thing you are describing or contrasting.

Here, が means but.

So the sentence structure is:

• あの店は高そうですが、
• That store looks expensive, but...

In Japanese, が often connects two clauses and can show contrast.

In this sentence, the contrast is:

• appearance: it looks expensive
• reality: it is not actually that expensive

実際は means actually, in reality, or as a matter of fact.

Breaking it down:

• 実際 = reality / actual condition
• は = topic/contrast marker

The は here adds a contrastive feeling, something like:

• as for the actual reality
• in reality, though

So the sentence contrasts:

• 見た感じ: it looks expensive
• 実際は: in reality, it is not

This は does not replace the topic あの店は. Instead, it highlights reality as a contrasting viewpoint.

それほど means that much, to that degree, or so much.

In this sentence, it is used with a negative:

• それほど高くありません
• it is not that expensive
• it is not so expensive

This is a very common pattern:

• それほど + negative

Examples:

• それほど難しくない = it is not that difficult
• それほど大きくありません = it is not that big

So それほど usually softens the statement rather than saying a complete no.

Because 高い is an い-adjective, and い-adjectives must change form before ありません.

The negative polite form is made like this:

• 高い → 高くありません

Why?

The い changes to く before certain endings.

So:

• 高い = expensive
• 高くない = not expensive
• 高くありません = not expensive (polite)

You cannot say 高いありません.

Yes. 高くないです is also common and natural in modern Japanese.

Compare:

• 高くありません = polite, a bit more formal
• 高くないです = polite, common in everyday speech

So the second half could also be:

• 実際はそれほど高くないです

Both are correct. The version in your sentence sounds slightly more formal or textbook-like.

Japanese often leaves out words that are already understood from context.

So after:

• あの店は高そうですが、

the listener already knows the sentence is still about that store.

Therefore, Japanese naturally says:

• 実際はそれほど高くありません

instead of repeating:

• あの店は実際はそれほど高くありません

The subject/topic is understood, so it is omitted.

あの means that, referring to something away from both the speaker and the listener, or something identifiable in context.

So:

• この店 = this store
• その店 = that store (near you / already mentioned)
• あの店 = that store (over there / more distant)

In this sentence, あの店 means that store.

In this sentence, yes, 高い means expensive.

But 高い can also mean high or tall, depending on context.

Examples:

• 値段が高い = the price is high / expensive
• 山が高い = the mountain is high
• 背が高い = tall

Because the topic is 店, and the sentence contrasts appearance with actual cost, 高い here clearly means expensive.

高そう is being used politely here, so です is added.

Compare:

• あの店は高そう。 = casual
• あの店は高そうです。 = polite

Since the sentence ends with ありません, which is polite, it makes sense for the first half to be polite too.

So the sentence keeps a consistent polite style:

• 高そうです
• 高くありません

Not exactly.

それほど高くありません does not directly mean it is cheap. It means:

• it is not that expensive
• it is not as expensive as it looks
• it is not very expensive

So the nuance is softer than calling it cheap. The speaker is only saying the store is less expensive than expected.