Thanksgiving dinner keeps getting more expensive. The cost of ingredients for the average meal for 10 people is up 13% from last year, to nearly $50, according to a supermarket survey by the American Farm Bureau Federation. Turkey prices have been ruffled up the most. This year a 16 pounder will set you back $21 and change, up 22% from 2010, according to the survey, which polled retailers in 35 states. Shoppers' wallets may take a bigger hit if they buy a fancy organic turkey and other gourmet items, experts say.

Why such a big jump? Higher grain prices have made feeding and raising livestock -- like turkeys -- more expensive, says Jack Plunkett, chief executive officer of Plunkett Research, a Houston based market research firm. What's more, bad weather throughout the country has caused shortages of some grains and produce. A drought in Texas, for instance, has pushed up the price of vegetables and beef, while flooding in the Northeast has made dairy products pricier. "We do have a food inflation problem," says Plunkett.

To avoid higher prices, experts say people should start shopping early -- like now. Supermarkets are offering early birds generous discounts to offset this year's rising turkey prices, says Teri Gault, founder of TheGroceryGame.com, a site that compiles coupons and sales for groceries. Supermarket chain Giant Eagle, for example, is selling some store brand turkeys for $.69 a pound through Nov. 16, down from $1.99 a pound; shoppers must also spend an additional $25 at the store. Through the same date Publix Super Markets in Florida is selling store brand turkeys for $.59 a pound, discounted from $1.49 a pound.

Indeed, because deals change weekly, shoppers will likely find more deals if they start shopping this week, says Gault, and many supermarkets will also offer coupons online or in the store for additional savings on certain items.

Finally, Stephanie Nelson, founder of CouponMom.com, recommends keeping an eye out for wallet busters; not all promotions this time of year are good deals. For example, many grocery stores advertise free turkeys for shoppers who spend a minimum amount at the store. While those deals might seem appealing, shoppers can end up spending more than they planned, says Nelson.