Takao
The Bunker Group
No.
HiMARS is about the minimum you need for the gold plated solution that will occur in the next 15 - 20 years. You'll see the posts above, I'm not convinced of the use of a land-based anti-ship missile. So ignoring that (adding that at the moment is gold plating a simple rocket launcher), you have something simple - a multiple launch rocket system.
Now, for something simple, a HiMARS is overkill. I mean, the BM-13 is plenty scary, let alone a Grad. We could just strap a bunch of unguided rockets to the top of a Hilux and crack on. Don't get me wrong, it sounds sarcastic, but for a short-range, tactical land fight, it's perfect. The GLMRS that HiMARS comes with is too much money for such a simple task, even with the nifty variants. What HiMARS brings that is important, and a simple strap on cannot replicate, is the PrSM. More importantly, it brings the PrSM growth plan.
Right now, Australia has no experience with long-range land strike. It's traditionally been provided by the bomber Sqn, but that's less a thing now due to survivability and cost. Navy is coming in to play, especially with Tomahawk, but still face a survivability question. Of course, in those same posts above you'll see that we suffer from a geographical problem, in that none of our likely targets are close. The answer is some form of very high speed, long range missile. Now, that could be ICBM or similar, that'd be almost perfect (excusing cost). But we have no experience with that.
PrSM starts that process. PrSM 1 gives the Land Force experience with 'big' missiles, long-range targeting, and shifts Army from it's 'M777 30km range is amazing' tactical mindset. 500 km range, simple seeker (and hence simple target set). Excellent. Note that the cheap options above all would need a second launcher to provide the 500 km effect - HiMARS can shoot both depending on mission. But still, 500 km is...not enough, although (critical to the point below), it can reach past our EEZ. PrSM 2 - 5 though, they extend range, speed and target set. Come PrSM 5, the Land Force will be capable of very long range, very high speed, cross-domain targeting. Which is impressive compared to now, and rivals anything the RAAF or RAN have/had.
Importantly though, in the 8 - 12 years it takes to build up to PrSM 5, a hypersonic missile can finish R&D, OT&E and come into service. Now you can have the first O5 in command of that unit having been a O4 Sub-unit commander of a PrSM 4/5 Bty and an O2 Tp commander of a PrSM 1/2 Tp. With all the targeting, tactics and 'stuff' around those command positions. That means a capability that can hit the ground running - a genuine cross-continental, hypersonic strike weapon capable of targeting across domains launching from Australia and capable of multiple modes of guidance - all done in a self-sufficient means. F-111's are awesome beasties - but this is orders of magnitude faster, more survivable and greater range.
So that's what HiMARS is. in the short term its a multi-mode rocket launcher (that all others need 2 launchers to do) and in the long term its a self-reliant, genuine capability that offers Australia a sovereign deterrence effect for the first time in our history. HiMARS is a bargin.
No.
I haven't seen any genuine open source figures that claim it's cheaper, the targeting requirement is well beyond most of our neighbours, and it's a poor option as it cannot reach a nation's EEZ. The Pacific Patrol Boat is a less complex ship compared to an Armidale, but still some neighbours need ADF support (which is more than ok). How they could sustain a OTH missile capability is beyond me.
And it can't reach the edge of the EEZ.....