WIP. 3.5e M&M Style

[noob]

And do you think wizard spells will be free? I'll give you a little hint of what's to come: wizard spellcasting will have large incremental costs that put these "chassis costs" on par with each other.

I spoke of the wizard chassis as meaning the hit dice, bab, skills and saves.
spells and the barbarian rage and uncanny dodge are not part of a chassis: those are class features

Of course I sure know you will not put wizard spellcasting(or druid spellcasting or bard spellcasting or cleric spellcasting or beguiler spellcasting or yet any other spellcasting going at least up to level 4 spells including paladin spellcasting) in this game or else it is just plain obvious nobody sapient will ever pick chassis over spells even if it costs your entire chassis(including putting the lowest value to each thing possible in the chassis such as having negatively progressing everything even for hit dice and having all the stats but one at 1(and the only stat not at one is the stat needed to cast spells)) to have spells.

Also you need to make skills that are basically just like spellcasting such as allowing to use survival for tracking anything no matter where it is or what it is if you beat a fixed dc(and letting people use survival to create thousands of tons of food while trapped in a lifeless wasteland) or other stuff like that if you let spellcasting in the game or else skills are just obsolete.

So as far as I know you should probably read mutants and masterminds then use the porting done by grod the giant because it does makes 3.5 m&m style and is way more balanced than doing regular 3.5 with point buy for class features and chassis (at least you should separate the chassis point and the class feature points so that barbarians like people does not find themselves unable to buy cool class features due to their bab and hp oriented chassis).
Unless you actually want 3.5 gurps style since it seems it is what you want to do since you are going to make powers with incremental costs not based on modifiers which is more gurps like than m&m like(since in m&m the cost of the powers is quite continuous and you can apply a lot of modifiers to them).
Maybe you should read gurps.

now let us say that a barbarian with his current chassis can buy all the normal dnd 3.5 barbarian powers in your system and that a crusader with his current chassis can buy all his non chassis powers and likewise for the rogue.
If he picks a wizard chassis (chassis does not include spells in my definition since it is a class feature and I sure hope you understand that) he could pick all the non chassis powers of a rogue(probably at a reduced cost since as a barbarian he already have uncanny dodge as well as trap-sense but without the cost reduction it would still cost only 4 points per level since a rogue spends 6 points per level in chassis) and all the non chassis powers of a barbarian and then have 2 points per level left to get a great portion of the non chassis powers of a crusader.(at least two third of those non chassis powers since the chassis of a crusader costs 3 points per level)
With all that it does not matters that person have a low bab and low hit points: he gets great survivability due to the crusader manoeuvrers and damage mitigation + barbarian rage and can dish out massively more than a regular barbarian thanks to rage + manoeuvrers + sneak attack which compensate widely his low bab.
Oh and if the powers of those classes did cost less than what was left after chassis deduction due to you wanting them to have points to spend on feats then that character will possibly be able to pick more of the crusader powers and have more feats than a regular barbarian.
Unless you decide "Ok now I am going to make mundanes have less cool class features than before so that people will play casters even more than before even if I will nerf those too" having four times more of those fighting class features is what you get if you decide "I am going to barbarian with wizard chassis" and four times more of those class features is way more useful than the barbarian chassis.

So it is clear that chassis should cost less and give less bonus points when dumped so that we do not have the situation where either you nerf barbarians and other mundanes or where you find yourself being better at the job of being a barbarian by getting a weak chassis.