The cheapness of these models means you'll have plenty of room for your big, expensive Battlesuit teams, Sky Rays, and what not. Some of the other options available are not great. If you have a gunline army, a Markerlight could be awesome, as could a team Leader with a bonding knife, or something else. Probably the best option they can take is the Devilfish APC. One of the best transports in the game, it can carry up to 12 models, and even vanilla it can kick out 5 S5 shots, although, you should probably upgrade it with a Smart Missile System. Anyway, with all of this talking, i need to give you an example. So, here is what I believe is the optimal Fire Warrior team.
6 Fire Warriors w/ Devilfish APC w/ Disruption Pod, Smart Missile System, Targeting Array, Multi-tracker - 180 points
I would suggest taking about 3 squads like this in any given 1.5K list, they can kick out some nice firepower. The Devilfish takes up the majority of the 180 points, taking up 12o of them. But still, it is a 12-11-10 vehicle that has a 4+ cover save against any shots from over 12" away (Disruption Pod), can fire, but not move, like a Fast Vehicle (Multi-Tracker), meaning it can fire 7 strength 5 shots if it moves 6" or less (Smart Missile System), and it has a healthy BS of 4 (targeting array). All in all, a pretty good unit, can take out many transport vehicles, and infantry, and if necessary, the Fire Warriors inside can disembark, and add their fire to the volley.