Is purchasing a tablet device for $700 considered extravagance, and does that diminish one's love for Allah or one's status in the Hereafter or one's faith, especially since I sought guidance through Istikhara and felt uneasy while searching for it?

Extravagance ( israf ) is exceeding the limit and adding beyond what is sufficient. It varies from person to person and from country to country. Whoever exceeds his capacity is considered extravagant. Buying a device to the detriment of a person is considered extravagance. As for indulging in permissible things without exaggeration, it does not diminish one's love for Allah. And whoever sees fit to practice asceticism in what does not bring benefit in the Hereafter has done well. Abandoning superfluous permissible things while preferring others to oneself is rewarded, and asceticism ( zuhd ) is abandoning what is not beneficial in the Hereafter, not abandoning the entire world.