I am very fond of building models (more so than painting them, actually). And I don't mean just assembling dozens of fire warriors, but creating something with a touch of individuality. Here is one of those examples (and there are more to come).
This one I call Lightbringer. He is a unique character inspired by Guardsman Marbo (Imperial Guard), although not as powerful. Lightbringer is a fast attack choice that is yours for 40 points. To cheap/to expensive? Well, let me know what you think:
Stats: WS4, BS4, S3, T3, W2, I4, A4, LD8, SV4+
Wargear: 2 pulse pistols, EMP grenades
Special rules: Independent character, Infiltrate, Move through cover, Fleet, Stealth, Hit and run, Eternal Warrior, Lucky, Not a leader
"Lucky"? Well, sometimes that is what it takes to survive out there. Lightbringer adds +1 to all save rolls (note that this does not affect the AP of weapons, an AP 4 weapon will still penetrate his armour).
"Not a leader"? No, he works best alone. If he joins another unit, he loses Infiltrate, Move through cover, Fleet, Stealth and Hit and run.
As you can see the model is a regular Fire warrior, but armed with two pulse pistols made from the front part of pulse carbines. Since he was raised among the Kroot, he also carries a Kroot backpack.
So, what is this guy good for? Well, the purpose was not to create a powerful character, but to make a fun addition to the Tau army list. He is supposed to be cheap, and with a little luck he might be of good use. In rare cases he might even be a gamechanger, which is true for any unit.