Resistance is a special ability, not an enhancement bonus
Here is what the rules say (emphasis mine):
In addition to an enhancement bonus, armor may have special abilities. Special abilities usually count as additional bonuses for determining the market value of an item, but do not improve AC. A suit of armor cannot have an effective bonus (enhancement plus special ability bonus equivalents) higher than +10. A suit of armor with a special ability must have at least a +1 enhancement bonus.
The special abilities do not always add an enhancement equivalent bonus, only usually.
If you then look at the table for armor special abilities, you can see that for some of them in the column "base price modifier" an enhancement bonus equivalent is given, for example spell resistance comes with a +2 bonus and a little footnote marker 1. That footnote informs you that
1 Add to enhancement bonus on Table: Armor and Shields to determine total market price
Others do not have an enhancement bonus and footnote, they instead have a fixed gp value cited. This is the case for acid resistance, at a price of "+18,000 gp". So in those cases, you do not add an enhancement equivalent bonus to increase the effective bonus that the weapon has for determining the price, you use whatever normal enhancement bonus (or bonus from other abilities) it has, and then add a lump sum. These enhancments have no "special ability bonus equivalent" to add. Your item needs to have at least a +1 bonus to start with, as per the rule given above.
This means for your example, you could create a +1 armor that would cost the armor's base price plus 1,000 gp for a +1 enchancemnt bonus, and then for each +66,000 gp, could add one of the greater resistances. The total price would be 332,000 gp plus the base price of the masterwork armor.
There is no stacking involved in this case. If you also had a +1 shield (costing another 1,000 gp plus masterwork base price), the shield's enhancement bonus would stack with the armors enhancemnt bonus of +1 for at total of +2 enhancement bonus to AC, because the rules inform you that:
Shield enhancement bonuses stack with armor enhancement bonuses.