No. The only official way to get the statue is to purchase the Legendary edition of Halo: Reach. However, there will definitely be some of the statues up for auction on ebay after the game comes out, but these will not be much cheaper then buying the game, and may even be more expensive.
Also, Bungie has stated that the Legendary edition (including the statue) is going to be very limited (as opposed to the Halo 3 Legendary edition which they are still trying to sell). There have already been a couple reports of retailers no longer selling copies of the Legendary edition because they are sold out. Nothing official has been said about whether all the copies are sold, but if you really want a statue, and don't want to press your luck on ebay, you should look for a copy soon.
One other option you have is to buy the legendary edition, and then try and sell the game. If you have a friend that wants the game, you could probably sell it for $50 (not sure of your country of origin, but in the US the limited edition of the game is selling for $70 new). You can also trade it back to Gamestop (or another used game retailer), but you will not get very much for that.
Also, the Legendary edition comes with a redeemable code for in game flaming helmets (and a couple other in game items). This alone could most likely be resold for $30-40 on ebay, because these are very desirable in the Halo community.
Really, you have two options. Buy the Legendary Edition and try to sell the stuff you don't want (or keep what will be a great game), or wait and try to buy the statue after the game is out.
Well, now according to the Halo Wiki the Mark VI helmet costs 300,000 cR and is unlocked at Brigadier, which itself requires 1,400,000 total credits. I suppose next month we'll see if that's accurate.
Best Answer
Suicide, or "Kamikaze" Grunts were added in Halo 3, and can be nasty little buggers if you're not paying close attention to them. That said, they do not run indefinitely. Each difficulty increases the amount of time that a Grunt can run. Mind you, on easy this distance still isn't short, especially if they are close. Here's a breakdown of the times and rough distances for each difficulty.
Easy
It took about 18 seconds from ignition of the grenades to explosion. Grunt was moving the whole time, though some repeated movements were made where it looked like the AI couldn't decide which way to go.
Normal
Normal also took about 18 seconds from ignition to explosion. Two grunts ran at me this time, both exploded apart from each other and at roughly the same time. Distance didn't seem to be much different.
*Note: The grunts did not explode at the same time, but they were pretty close to one right after the other.
Heroic
Heroic had an additional 6 seconds, bringing it up to a total of 24 seconds from ignition to explosion. That additional time adds a lot of distance and requires a lot of open space to run away from.
Legendary
There was an additional 4 seconds in Legendary when compared to Heroic, bringing the final total up to 28 seconds. The distance covered here is very long for most any open stretch in Reach, and to run away, you will likely need to do a few circles (or jump on a platform, see below).
Premature Explosion
Grunts will blow their payload if they die, are too far away from you or if they are unable to reach you. This means that, if you have a jetpack or a platform to jump on, they will blow themselves up immediately. Also, a simple headshot will drop them quickly.