Ride and practice in free riding areas instead of going to the moto track every time and paying to get in. Choose just one day each week to moto, if possible, and spend the rest of your riding time elsewhere where you don't have to pay. This saves on the expense of the gate fee, gas getting to and from the track, and food.
Avoid last-minute trips to the convenience store! Have a list of everything you need for racing and riding and buy these things at less expensive places (WalMart, Sam's Club, Costco, etc.) beforehand instead of paying a premium on the way to ride or race.
Be smart; fill gallon water jugs at home and stock the cooler with ice out of your own freezer. Prepare your own food at home beforehand to eat on the way there and at the race site; this is healthier than the junk at trackside concession stands and less expensive than eating out.
Plan ahead on buying gas. Take 5 gallon containers and fill them up at a place where gas is cheaper. Because we buy groceries at Safeway, we sometimes get up to 20 cents off per gallon!
Cut costs on magazines by subscribing for the year rather than buying each issue at the grocery store. I still do this and just put them in my travel knapsack to read when I'm at the airport or on the airplane.
Ride with a buddy to split gas and hotel costs. IF the weather is nice, pitch a tent or sleep in the van to save $100 per night over a hotel room.
If you're flying to the races, book your flights early; usually you get a better deal at least 2 to 3 weeks out.