This is the (in)famous movement rule for prepositions. It's a useful rule, but you have to be careful about what the rule actually says and there are exceptions you have to keep in mind. First, it's not movement in general, but movement to or placement at the location. So if the location describes where the movement is taking place, but not a destination, then you use the dative, not the accusative. For example "Der Junge rennt in der Küche" says the boy is running (around) in the kitchen, but "Der Junge rennt in die Küche" says the boy is running into the kitchen. English has two different prepositions here, but sometimes there is no difference in English, for example with "between" or "under". Second, the rule only applies to certain prepositions, and others take a specific case whether there is movement or not. An example is aus which always takes dative, unlike its opposite in which follows the rule. Third, and this is where your example falls, if the preposition is involved in a figure of speech, in other words not taken literally, then just ignore the movement rule and memorize which case the phrase uses separately. In this case the phrase is auf den ersten Blick; you don't mean that whatever it is is literally "on" a "glance", so this is a figure of speech. And so the movement rule does not apply and you just have to memorize that auf uses the accusative in this case. There are hundreds if not thousands of such figures of speech, and while there are some rules of thumb which can help you to remember which case to use each time, there is still going to be some memorization involved. The rules of thumb can be useful as long as you keep in mind that they are rules of thumb and not actual rules. If you have to guess, then pick accusative because that seems to be the most common in these figures of speech, but there are, of course, many times where a figure of speech uses the dative.
Prepositions normally form an adverbial phrase, in other words a phrase that functions as an adverb. But an adverb can either describe the verb itself ("he moved slowly") or the rest of the sentence ("unfortunately, he moved"). In your example the phrase functions as an sentence adverb; it doesn't say anything about the main verb (bieten) but the sentence as a whole. I think such cases will nearly always be figures of speech and so the movement rule will not apply. Note that many dictionaries cover figures of speech either as separate entries or under the main word of the phrase. So Wiktionary has a separate entry for auf den ersten Blick. A dictionary should tell you which case is appropriate for the particular phrase. In this case there's no need since the accusative is baked into the phrase itself.
