Overall, it looks like
three3pryme was pretty right. Just pulled this right out of the program code, level tells you starting from which mission you can use this item. Level 0 is "Training Day".
// GLADIATORS \\
[SbKbCore loadShip:SHIP_GLADIATOR_PLASMA withTag:ALLY_SHIP_GLADIATOR_PLASMA price:5000 andHealth:2000 level:0];
[SbKbCore loadShip:SHIP_GLADIATOR_LASER withTag:ALLY_SHIP_GLADIATOR_LASER price:8000 andHealth:2500 level:1];
[SbKbCore loadShip:SHIP_GLADIATOR_MINI_GUN withTag:ALLY_SHIP_GLADIATOR_MINI_GUN price:10000 andHealth:3000 level:3];
// CENTAURS \\
[SbKbCore loadShip:SHIP_CENTAUR_PLASMA withTag:ALLY_SHIP_CENTAUR_PLASMA price:8000 andHealth:3000 level:0];
[SbKbCore loadShip:SHIP_CENTAUR_LASER withTag:ALLY_SHIP_CENTAUR_LASER price:13000 andHealth:3500 level:1];
[SbKbCore loadShip:SHIP_CENTAUR_FLAK withTag:ALLY_SHIP_CENTAUR_FLAK price:15000 andHealth:4000 level:2];
[SbKbCore loadShip:SHIP_CENTAUR_MINI_GUN withTag:ALLY_SHIP_CENTAUR_MINI_GUN price:18000 andHealth:4500 level:3];
[SbKbCore loadShip:SHIP_CENTAUR_HYBRID withTag:ALLY_SHIP_CENTAUR_HYBRID price:23000 andHealth:5000 level:4];
[SbKbCore loadShip:SHIP_CENTAUR_SPECIAL withTag:ALLY_SHIP_CENTAUR_SPECIAL price:50000 andHealth:6000 level:5];
// UTILITY \\
[SbKbCore loadShip:SHIP_ORE_MASTER withTag:ALLY_SHIP_ORE_MASTER price:10000 andHealth:450 level:2];
[SbKbCore loadShip:SHIP_WELD_MASTER withTag:ALLY_SHIP_WELD_MASTER price:15000 andHealth:1500 level:3];
// CAPITAL \\
[SbKbCore loadCapitalShip:SHIP_CRIUS withTag:ALLY_SHIP_CRIUS price:50000 andHealth:4000 level:4];
[SbKbCore loadCapitalShip:SHIP_HYDRA withTag:ALLY_SHIP_HYDRA price:80000 andHealth:6000 level:5];
[SbKbCore loadCapitalShip:SHIP_CERBERUS_HYBRID withTag:ALLY_SHIP_CERBERUS_HYBRID price:100000 andHealth:10000 level:6];
[SbKbCore loadCapitalShip:SHIP_CERBERUS_ANTI_MATTER withTag:ALLY_SHIP_CERBERUS_ANTI_MATTER price:175000 andHealth:10000 level:6];
[SbKbCore loadCapitalShip:SHIP_AEGAEON_HYBRID withTag:ALLY_SHIP_AEGAEON_HYBRID price:750000 andHealth:32000 level:7];
[SbKbCore loadCapitalShip:SHIP_BEHEMOTH_MASS_DRIVER withTag:ALLY_SHIP_BEHEMOTH_MASS_DRIVER price:15000000 andHealth:100000 level:8]; <- If only someone could change that value after the "price" tag, haha.

// TURRETS \\
[SbKbCore loadTurret:TURRET_ARTILLERY withRange:0 rechargeTime:24 energy:20 damage:50 price:3000 level:0];
[SbKbCore loadTurret:TURRET_PLASMA withRange:350 rechargeTime:12 energy:15 damage:20 price:2000 level:0];
[SbKbCore loadTurret:TURRET_LASER withRange:450 rechargeTime:9 energy:20 damage:30 price:3500 level:1];
[SbKbCore loadTurret:TURRET_FLAK withRange:400 rechargeTime:15 energy:30 damage:15 price:4500 level:2];
[SbKbCore loadTurret:TURRET_MINI_GUN withRange:500 rechargeTime:3 energy:5 damage:25 price:5500 level:3];
[SbKbCore loadTurret:TURRET_MISSILE_LAUNCHER withRange:650 rechargeTime:100 energy:400 damage:180 price:6500 level:4];
[SbKbCore loadTurret:TURRET_ANTI_MATTER withRange:650 rechargeTime:15 energy:50 damage:180 price:12000 level:6];
[SbKbCore loadTurret:TURRET_REPAIR withRange:800 rechargeTime:10 energy:5 damage:0 price:8000 level:3];