Its difficult to put an exact number "economics" on maintaining greens at 10 or 11. Many good reasons for increased budgeting were made in previous posts'. But one has to look at many factors that are unknown in any given season, especially environmental factors; heat, pest, disease pressure, as well as what substrate you have under the turf. Additionally, is the turf bent or bermuda.
From the bermuda side, I have helped maintain "Champion Bermuda" for 3 seasons now. It has been extremely challenging while also difficult or lets say a big learning curve. Economically speaking, maintaining this turf is difficult to pinpoint because our greens may require more or less imput than a course 30 miles down the road because of totally different environmental conditions. Were talking micro and macro environments which are additionally different through a single golf course. It also depends on what kind of equipment inventory you have on hand.
I'll cut to the chase. We had to purchase a new (sand) topdresser for more precise output. Four walking greensmowers, because when your mowing a hair below an 1/8, triplexes just dont give you consistency and you can definitely see the difference. A new spray rig, for foliar rather than granular applications. Additionally, a good aerifier would be needed because a tine greater than a "needle tine - 1/8" has a residual of 2-3 weeks. We already had a verti-drain so we didnt need a new device, but your looking at 14 - 18K.
Throw in the man power and your spending some cash. Not to mention going to chemical applications, increaded sand applications (for smoothness), and handwatering during times of stress. All in all, annually your looking at 30 - 50K additional budget. The range is based on conditions unforeseen, such as bermudagrass decline, which inturn cause a lot of screeming from a membership. Maybe one should add an addition 5K for Doctor visits!