Reduces prices of first aid kits. (#3221)

<!-- Write **BELOW** The Headers and **ABOVE** The comments else it may
not be viewable. -->
<!-- You can view Contributing.MD for a detailed description of the pull
request process. -->

## About The Pull Request
Standard: 750 -> 400
Brute/Burn: 1250 -> 700
Oxy/Tox: 1250 -> 500
Rad: 1000 -> 500
<!-- Describe The Pull Request. Please be sure every change is
documented or this can delay review and even discourage maintainers from
merging your PR! -->

## Why It's Good For The Game
Those prices weren't really that affordable in-game. Spending a 1000
credits on a single medikit is kinda goofy. This fixes that, in hopes
that medikits are more used in general.
<!-- Please add a short description of why you think these changes would
benefit the game. If you can't justify it in words, it might not be
worth adding. -->

## Changelog

:cl:
tweak: Reduced the prices of first aid kits.
/:cl:

<!-- Both :cl:'s are required for the changelog to work! You can put
your name to the right of the first :cl: if you want to overwrite your
GitHub username as author ingame. -->
<!-- You can use multiple of the same prefix (they're only used for the
icon ingame) and delete the unneeded ones. Despite some of the tags,
changelogs should generally represent how a player might be affected by
the changes rather than a summary of the PR's contents. -->

code/modules/cargo/packs/medical.dm

@@ -9,42 +9,42 @@
 /datum/supply_pack/medical/firstaid_single
 	name = "First Aid Kit Single-Pack"
 	desc = "Contains one first aid kit for healing most types of wounds."
-	cost = 750
+	cost = 400
 	small_item = TRUE
 	contains = list(/obj/item/storage/firstaid/regular)
 
 /datum/supply_pack/medical/firstaidbruises_single
 	name = "Bruise Treatment Kit Single-Pack"
 	desc = "Contains one first aid kit focused on healing bruises and broken bones."
-	cost = 1250
+	cost = 700
 	small_item = TRUE
 	contains = list(/obj/item/storage/firstaid/brute)
 
 /datum/supply_pack/medical/firstaidburns_single
 	name = "Burn Treatment Kit Single-Pack"
 	desc = "Contains one first aid kit focused on healing severe burns."
-	cost = 1250
+	cost = 700
 	small_item = TRUE
 	contains = list(/obj/item/storage/firstaid/fire)
 
 /datum/supply_pack/medical/firstaidoxygen_single
 	name = "Oxygen Deprivation Kit Single-Pack"
 	desc = "Contains one first aid kit focused on helping oxygen deprivation victims."
-	cost = 1250
+	cost = 500
 	small_item = TRUE
 	contains = list(/obj/item/storage/firstaid/o2)
 
 /datum/supply_pack/medical/firstaidtoxins_single
 	name = "Toxin Treatment Kit Single-Pack"
 	desc = "Contains one first aid kit focused on healing damage dealt by heavy toxins."
-	cost = 1250
+	cost = 500
 	small_item = TRUE
 	contains = list(/obj/item/storage/firstaid/toxin)
 
 /datum/supply_pack/medical/firstaid_rad_single
 	name = "Radiation Treatment Kit Single-Pack"
 	desc = "Contains one first aid kit focused on reducing the damage done by radiation."
-	cost = 1000
+	cost = 500
 	small_item = TRUE
 	contains = list(/obj/item/storage/firstaid/radiation)