I have noticed that the market place is for those who have the highest amounts of crowns, but what about those who don't have that much to spend on 100 energy? I have thought about this and came into a conclusion which could benefit everyone - Auto-Balance-Combine feature.

Auto-Balance-Combine
(ABC for short)

This would cause several knights to combine their offers into one big offer to complete deals that need huge amounts of crowns. This means that a knight who has otherwise insufficient funds to pay for 100 energy package from the market, will be able to do so. An example:

1st knight = 1000 crowns for 100 energy
2nd knight = 1000 crowns for 100 energy
3rd knight = 500 crowns for 50 energy
4th knight = 500 crowns for 50 energy
5th knight = 100 energy for 1000 crowns
6th knight = 100 energy for 1000 crowns
7th knight = 200 energy for 2000 crowns

Limit of ABC is 4 knights and the game calculates and matches them automatically. Now the 5th knight is willing to sell 100 energy for 1000 crowns so the game matches the offer with the 1st knight if he or she did not decide to combine. 2nd knight will get the same match unless the 1st and 2nd combine their offers which makes them a match with the offer of the 7th knight. The 7th knight then decides to complete the deal with those two if so wished. 3rd and 4th knight combined their offers so they are a match with 6th knight who may decide to take their combined offer. You could have a button to allow combined offers so you just would need to decide which offer you are to take.

Another method is to make the game decide it randomly so everyone has an equal chance to gain energy without having to fear from insufficient funds. Another option would be to add a sum into an offer of your choice to complete them and gain your share of the deal which depends from the added sum of energy/crowns.

Material Mist Energy Transformation
(MMET, pronounced "Emmett")

A small suggestion to gain a slight energy package could come in a form of common materials that you don't need. Instead of selling them, you could transform them into small packages of energy with the cost of the material lost with/without some crowns paid. An example:

Set of 5 materials + 100 crowns = 5 energy (100% success / right recipe)
Set of 5 materials + 100 crowns = 2 energy (50% success / wrong recipe)
Set of 10 materials + 100 crowns = 10 energy (100% success / right recipe)
Set of 20 materials + 100 crowns = 10 energy (50% success / wrong recipe)

You have gained a set of materials that you may not need. You are low on energy so you decide to transform that set into energy just in case you need a little extra on the road to Core Terminal. You are at the Bazaar and you visit an NPC whom will do the transformation for you and seal the produced energy into your tank. This could cost you some crowns, but not too much since you already lose the materials that you could have sold. The setback could be that if you insert materials in a wrong way, the recipe (much similar to the themes in which way you return the minerals) will backfire and you are given 50% reduced amount of energy.

Another method could be that the outcome changes into random energy reward which does not depend from any recipies. You just drop the certain set of 5 or 10 or 20 materials and hope for the best outcome. Here however the cost could be higher to balance this properly.

Energy gained thru MMET feature would be mist energy and thus you could end up with nothing or at least lose some of the energy if the mist energy tank is full or almost full.

Basicly any mix and match of these two are welcome in my opinion. Just not to forget that OOO needs their payments too every now and then which is cool. I like to support a game that I like, but what the Energy System lacks is an optional/additional "Give-&-Get" feature just like MMET and ABC to balance and keep the game more fun to play even if you think you run out of crowns or energy and need 5 or 10 extra at the moment. Maybe add a cooldown timer for the MMET to balance it even more? Usage of minerals could be good too if materials are not so good idea or maybe add a totally new item type for this job?