first trade up cost about 7.5$, you buy 9 low float MAG-7 | Metallic DDPAT and 1 Industrial Grade from the St. Marc collection (factory new doesn't matter which one you pick) and that's a 20% chance to hit for 25$

If you hit the St. Marc trade up and want to keep going for the purple than buy 9 Desert Eagle | Urban Rubble or Sawed-Off | Amber Fade at .03 or below for best float outcome and thats a 25% chance at 115$

so with all that said you could turn 7.5$ from the first one into 25$ than invest 9$ more for the blues from the train collection and turn the 25$ into $115

all in all like a 16.5$ investment for a possible 10x