If an investment is almost certain to deliver a high payback why not go out on a limb and find the money to pay for it?  In the case of your business you know what your capabilities are.  You know if you can successfully "pull off" a change that will improve the business performance.  Yet time and again companies refuse to invest in the sort of help they need to make those improvements because, "it's just not in the budget this year".  I know that finance people and accountants will think me crazy.  But give this logic a bit of consideration. They are coming from a narrow perspective that fails to see the big picture.  Even the maintenance, engineering and operations people may be doing the same thing.  They are thinking like managers not leaders.

Managers maintain the status quo.  Leaders rock the boat with change.

Consider that an improvement in maintenance management practices (and indeed in methods being used) in many companies will provide a savings of 10 - 20% of maintenance costs.  Much of that can be found in the first year of making changes - often quite easily.  The more reactive your approach to maintenance, the greater the potential for benefit and the faster you'll see it materialize.  If your maintenance costs are in the range of 15 - 25% of operating costs (which isn't unusual) that translates to a costs savings to overall operations of 1.5 to 5%.  Assuming production levels remain constant that's a significant boost to the company's before tax profit margins.

Now consider that you can actually improve production levels with some of these improvements.  The figures here will vary considerably but that too will add to profit margins. 

So what sort of investment does that require?  A maintenance management improvement initiative at a plant can cost you on the order $250k to $500k per year.  If that is paid for from the 1.5 to 5% cost savings, your operating costs will be no more than $10 to $16M in order to pay for it on a break even basis.  Not many plants and operations work with that small an operating budget, so the opportunity in most cases is huge.  The costs to make the changes won't grow much with the size of your operations, but the potential for benefit grows substantially. 

If you are afraid you don't have the money in your budget to cover the improvements, then you clearly have no confidence in your ability to make the changes necesasry to gain the benefits.  Perhaps past experience has shown that your site can't make change easily.  Your consultants can certainly help with that if they are any good.  Why not put them to the test - ask them to put some skin in the game.  That will separate the wheat from the chaff.  The good ones will accept the risk in order to share in your payback. 

In any event, the fear that you can't make the changes successfully must be dealt with.  You'll need to get to the bottom of why that fear exists.  And that must be done at a very senior level.  Finance and accounting people will look only to revenues and costs with a primary focus on costs.  They tend to be skeptical about claims by others that they can actually reduce costs.  Maintenance and operations people tend to look only at their budgets.  Their performance many even be tied to their ability to stick to their budget numbers (compliance to budget).  That's actually a dis-incentive to taking a risk on something that has a high probability of working.  It discourages entrepreneurial risk taking (which isn't gambling as some might believe).  The operations manager might want the added security of being able to meet production quotas, but be unwilling to pay for the improvements.  His incentives may be in conflict.  The maintenance manager may have his budget over-extended - most are these days. That's often due to short sighted cost cutting and failed attempts at "lean".

You'll make no progress until as an organization you get past fears such as these.  It often requires a very senior set of eyes to see the big picture.  Entrepreneurs think this way.  Many others in business do not - that's why they are employees.  If you want to show that you are a leader - take some risks.  Be smart about it, but take risks.  The fears you are feeling about budget, quotas, will it work, etc. are only there to test your mettle.  They actually reveal that there are opportunities if you'll accept the fear of the fear you might be creating.