Estoy tomando un curso de español.
If one wanted to say "I'm planning to buy it later", which would be better in Mexico?
(a) Estoy planeando comprarlo más tarde.
(b) Pienso comprarlo más tarde.
Both get the idea across and are perfectly understandable. However, translation b is more colloquial.
(a) Estoy planeando comprarlo más tarde.
This is the most literal word-for-word translation. Usually these are the most awkward, if at all even a proper sentence.
(b) Pienso comprarlo más tarde.
This is a translation that better translates the idea behind the words. Pienso means think but don't interpret that word literally. This doesn't mean that you're just thinking about maybe buying it; it still means you're planning on it.