Space Marines Command Tanks are here, and Warhammer World is the first place you can get them. With that said, they are sold in a single box together with one additional sprue over both tanks to upgrade them with several Space Marine chapter bits.
Check out some of the rules and weapon options for these guys!
via UnkyHamHam on Bolter and Chainsword
You must take them both together. And they are the cost of 4 Thunderfire cannons...
via a reader on Faeit 212
Space Marine HQ Command Tanks sold in one box together with only one sprue to upgrade both base tanks (think the price is £75). They have either the space marines, blood angels, dark angels or space wolves faction. They are chosen together as one HQ slot but operate as separate units on the battlefield.
Rhino Primaris gets an Orbital Array which either brings in one reserve unit automatically or calls an orbital alpha strike (massive blast orbital bombardment) and also has a serveo-skull hub which once per game, per ability, gives one unit in 12” snapshots (including overwatch) at full BS OR fearless OR vehicles only, restore 1 hull point on 2+. Comes with twin-linked plasma gun and transport capacity of 6. No information on points cost yet for either tank.
Excelsior has Aquila Aegis field which is effectively extra armour with inbuilt 6++. One unit within 12" (can be upgraded to 18" for 10pts) gains one special rule for the turn from: counter-attack, fearless, hit & run, Interceptor, preferred enemy, sky fire, spit fire or tank hunters. Can take a combi plasma. Comes with 2 twin linked lascannons, a grav cannon and grav.
If an Excelsior is within 24” of one or more friendly primaris then +1 BS to excelsior. Both tanks can take the usual stormbolter, hunter killer, extra armour and dozer blade (rhino only) upgrades.
Additional Pics from ebay where its already for sale for double the Warhammer World cost.