A slightly older boxset is the Start Collecting: Vanguard Space Marines. It contains everything you need to bring Phobos armoured marines onto the battlefield.
Unfortunately, the Suppressors and the Lieutenant in Phobos Armour are not yet available to buy separately on the Games workshop website (though they are available on eBay). As such I will be making what I feel are some speculative prices for these two units.
In Start Collecting: Vanguard Space Marines you will receive; 1 Lieutenant in Phobos Armour, 3 Suppressors, 3 Eliminators, and 10 Infiltrators.
Considered separately this boxset prices up as follows.
1 Lieutenant in Phobos Armour = £22.50*
3 Suppressors = £30*
3 Eliminators = £30
10 Infiltrators = £35
All combined, at the recommended retail price these items are worth £117.50. With the boxset costing £60 this is a saving of £57.50, which is close to 50% off which is great!
But how valuable are these units like on the tabletop?
Overall this boxset has some great units that have the potential to synchronise very well.
The Suppressors are perfect for taking out enemy commanders with their bolt sniper rifles. While Suppressors can make quick work of light tanks and monstrous creatures, just don't expect them to take out Landraiders or Baneblades.
In short, this is a boxset that has great value for money and will perform well on the tabletop as either the start of a new army, or an addition to an old one.
(*Prices based on similar units)