The entire purpose of Messages.yml is customization.
You can customize your entire DynamicEconomy experience using this file. Instead of me, as a developer, deciding what DE will output when commands are used, you can choose.
So, change the preset messages here with any color codes you'd like, and they will appear wherever they're used! Here's the messages.yml fields:
no-permission: '&2You do not have permission to use this command.'
invalid-command-args: '&2You entered the command arguments in the wrong order, or your amount was invalid. Try again. '
wrong-world: '&2This world does not have access to this command.'
below-min-y: '&2You are too deep underground to access the economy!'
above-max-y: '&2You are too high up to access the economy!'
loans-disabled: '&2The Bank is not available for loans at this time.'
stock-on: '&2Stock is turned on.'
stock-off: '&2Stock is turned off.'
boundaries-on: '&2Boundaries are turned on.'
boundaries-off: '&2Boundaries are turned off.'
item-doesnt-exist: '&2This item does not exist. '
item-has-no-durability: '&2This item has no durability.'
no-armor-equipped: '&2You do not have any armor equipped'
no-helmet-equipped: '&2You do not have a &fhelmet &2equipped'
no-chestplate-equipped: '&2You do not have a &fchestplate &2equipped'
no-leggings-equipped: '&2You do not have &fleggings &2equipped'
no-boots-equipped: '&2You do not have &fboots &2equipped'
banned-item: '&2This item is banned, and not allowed to be purchased in the economy.'
cannot-buy-all: '&2Stock Disabled, cannot use keyword ''all'' '
negative-buy-amount: '&2Cannot buy a negative amount!'
negative-sell-amount: '&2Cannot sell a negative amount!'
not-enough-money: '&2You do not have enough money to purchase this.'
not-enough-stock: '&2There is not enough stock of this item.'
purchase-success: '&2Purchase Success!'
not-within-region: '&2You are not within an economy region!'
sale-success: '&2Sale Success!'
stock-added: '&2Stock succesfully added.'
stock-removed: '&2Stock succesfully removed.'
no-region-selected: '&2No region selected!'
region-expanded: '&2Region expanded!'
region-contracted: '&2Region contracted!'
max-loans: '&2You have the maximum number of loans allowed.'
loan-account-not-found: '&2The Bank is not available, contact your server admin'