少なくとも十ドルはすると思います。
I didn't get why it is here. Could I rewrite the sentence without する?
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Sign up to join this community「(amount of money) + する」
means:
"~~ costs (amount of money)"
That is probably the most common way of describing what a thing costs.
"I think it would cost at least 10 dollars."
You could say just about the same thing without using 「する」, but it will not sound nearly as natural. For instance, you could say:
「少なくとも10ドルだと思います。」
「少なくとも10ドルは取{と}られると思います。」
I would be shocked if they did not teach 「(amount of money) + する」 in Japanese-as-a-foreign-language, seriously. It is an expression we use on a daily basis.