PF Construct Mod Ability Score Enhancement limit?

[unseenmage]

Does the Ability Score Construct Modification from Pathfinder have a limit?
What if you're using it in a 3.5 game?

[unseenmage]

With each ability score mod costing 5,000gp I assume I would take the Wealth by Level, divide by four to find the most I can spend on any one given item (can't remember if that's a houserule), subtract the construct's MP, then divide the remainder by 5,000. That should give me how many ability score modifications a character can buy for a single construct at a given level.

That this is roughly +10 at level 20 seems to work out.