Exiling things is great, answering a permanent type your color cant usually answer is great
It is not an exaggeration to say that a difference of a single point on the PSA grading scale can represent hundreds, even thousands of euros in difference
The land base is another easy way to reduce the cost of Commander decks right now, as so many lands have steadily risen in price over the last few years that if you want to run mostly non-basics, it's going to take up a huge portion of your budget.
However, since this is a beginners guide, this is not recommended, as the more colors you add, the more difficult it becomes to cast your various cards, as your mana requirements will become more and more demanding and difficult
Overall, you're likely to get more usage out of Moltres and Dragonite for their Pokmon Powers (energy searching and healing) than actually using them to fight
Kydele, Chosen of Kruphix can generate a ton of mana if youre drawing extra cards