This is still an issue. Laser Turret Damage 7 for example only costs one of each bottle.
Some infinite techs in Rampant start at an earlier level than in vanilla, but this wasn't accounted for in the formulas. Continuing the example, Laser Turret Damage's formula is "(L-7)*20000", but since it starts at level 7 it obviously becomes "0*20000" which is just 0.
Good fixes are to either change it to (L-6), which would result in all levels going up by 20,000, or to add a non-infinite seventh technology level and make the infinite levels start at eight. The latter would prevent the infinite tech scaling from changing at all to how it is now, but would allow the seventh level to be obtainable before launching a rocket (though with how cheap they are, launching a rocket gets you ALL of these seventh levels IMMEDIATELY, which is much more exploity).
The entire list of technologies that this issue exists for:
Bullet Damage 7
Rocket Damage 7
Shotgun Shell Damage 7
Laser Turret Damage 7
Grenade Damage 7
Refined Flammables 7
Cannon Turret Damage Bonus 7
Capsule Turret Damage Bonus 7
Character Health Bonus 7
Gun Turret Damage 7
Landmine Damage Bonus 7
Rocket Turret Damage Bonus 7
Shotgun Turret Damage Bonus 7