Mainers pay $25 extra per year for those clever — or sometimes inscrutable — license plates known as vanity plates. They cost far more in Abu Dhabi, the richest city in the world. Businessman Saeed Khouri paid $14 million for the “1” tag, and his cousin, Talal Khouri, paid $9 million for “5.”

The state of Maine made $2,750,874 from the sale of vanity plates in 2010. The Legislature raised the fee from $15 to $25 in September 2008, and the revenue went up accordingly.

That may suggest to the new governor and some members of the new Legislature that charging more for vanity plates would be a good way to increase revenues and help balance the budget in these troubled times. Texas charges $195 and expects its annual take from the fancy plates to reach $25 million in five years. Minnesota charges $100. California charges $98. Next-door New Hampshire charges $40.

But Cathie Curtis, who keeps track of the Maine figures as deputy secretary of state for the Bureau of Motor Vehicles, warns that there’s a limit to how high the fees could go. She notes that the number of vanity plate holders had been growing steadily for many years to a high of 112,456 in 2008. But when the annual charge was nearly doubled in 2009 sales began dropping, down to 109,810 in 2010.

And, besides, Maine isn’t oil-rich Abu Dhabi or even Texas. She warns that another jump in the Maine fee could bring a drop in total revenue.

The low-number plates may be something else. Maine calls them “out-of-rotation” plates and charges only a one-time fee of $15, up from $5 a few years ago. Many people like them and might pay a good bit more for the privilege, possibly on an annual basis. And there seems to be no justification for the holder of a low-number plate to pass it on to relatives or friends for an indefinite chain of no-pay ownership.

Trying to find new revenue by fiddling with the license plate fees won’t produce a huge windfall, but it is worth further consideration.

On the other hand, the special plates come with a down side. They can be easier for a police cruiser to spot if the driver exceeds the speed limit or drifts over the centerline or commits some other infraction.