looks like a solid list and build. A couple suggestions and concerns.
if you want 12s you will want <200kv motor. I know DIYes is getting a 190kv sensored motor option soon. The R-Spec from enertion is another option, and there’s always the SK3’s from HK.
You should read up on the 60k ERPM limit to avoid damaging your VESC - might decide to go w/ a different motor setup and lower # series batteries? I usually go 8-10s to be a bit more cautious and not push my VESC’s.
Charger - that’s for a SPACE cell - look at the iMax/SkyRC B6ACv2 if you want an inexpensive but good starting charger that doesn’t need a AC to DC power supply. Slower than an icharger or similar, but the non-clones are pretty nice!
Tx/Rx - i would go with the tried/true GT2b myself - $25, then print your own enclosure (badwolf, master cho, baby buffalo, etc.) or have one printed from 3dhubs for a few $ more.
BMS - i’d skip until you get going. Use lipo or similar to start and upgrade later.
skip the battery meter as well. Get a low voltage alarm instead to alarm/yell at you when voltage on any cell in the pack gets below 3.x volts (set in alarm where you want - i usually do 3.7 or 3.6v).
like this - http://www.hobbyking.com/hobbyking/store/_90762__Turnigy_Lipo_Battery_Voltage_Tester_2_8S_and_Low_Voltage_Buzzer_Alarm_AU_Warehouse.html
Batteries - i personally like multiple thinner batteries w/ a harness to run in series vs a single big 6s/8s/12s battery. cheaper, modular (if one has an issue) and lower profile under the deck. so some 3s x 3 for 9s, or x4 for 12s. i shoot for <30mm thickness on their “C” size on HK.
misc - i’d look at a loop key and pick a single type of battery connector. I like XT90’s, but just pick one as in the long run it’ll help you a lot to simplify.
my .02 - HTH and GL!