I dont think its a good idea to cap budgets.ive already proposed a 100 million a year budget to keep things competitive... about 3 months ago on this site... everyone thought it was a dumb idea, but i think its a great one...
Firstly, that means the FIA will have to interfere/regulate the business of the Teams as a going concern.
Secondly, it can not be policed without the aforementioned interferance etc.
A law/rule, which can not be policed is a bad one however you look at it.
Thirdly, if the cap was $100m, say. Team B can only raise $1000 to go racing with and Team A have or raised $100m. How is that different from the current situation. Team B will still almost certainly be at the back of grid and have no chance. The fact that the budget is capped will be of no use Team B. Every season, the argument becomes "the bugdet should be capped at a lower figure to help the struggling or back-of-grid Teams".
What is needed is a scenario where 'Mega-Bucks' Team has as much chance of being at the back of the grid as 'On-a-Shoestring' Team, REGARDLESS of budget or however much they spend. One way to achieve this is to have clearly defined rules/laws and widen the areas for the teams to be inovative.
The alternative is to regulate or stipulate that all cars must be Fiat Pandas, 1.2L, V2, unmodified production vehicles using Pirelli tyres supplied by tyres'r'us & sons (at least this way you will have more or less caped how much can be spent on the car and ensured they are all exactly the same).