It would help if you would list the current prices and specs:
A. $10 for 3,500 CE
B. $13 for 1,000 CE, 2-week elevator pass, Silver Key, 7-day heat amplifier, and miscellany

I would go with Option A, because
* Heat amplifiers are worthless to me, as heat is never the limiting factor in my crafting.
* Elevator pass is worthless to me, as I have multiple accounts and more than enough mist energy (ME) already.
* The Silver Key has some crown value, but not enough to make up for the difference in CE.

As soon as you spend this money on your account, your account will be marked "paid", and you will be able to make a second account, on the same computer, with its own ME stream. So then you'll have 200 ME per day on two different knights. For me, this is more than enough playing time each day. What about you? If not --- maybe you want to play the game all day long for the next two weeks straight --- then the elevator pass could be worth considering. But you can also buy that alone for $6.

Well, the 1,000 CE that you get from the Explorer Pack is enough to upgrade one 3-star item to 5 stars, if you also use as much ME as possible. So, unless you have some CE sitting around, you're going to need to farm crowns to get another 1,000 CE, just to upgrade your Autogun and Antigua. While you're doing that, you'll easily get enough heat. Heat is simply not the rate-limiting factor, unless you're spending CE rapidly. So, based on what you've told us, I think that you might regret buying the Explorer Pack. Anyway, good luck.