I recently had a hamburger whose main ingredient was Truffle shavings ($50.00 btw) - I loved the flavor, but can't afford to buy the real ones, any substitutions with similar flavor?
Agreed with Joe. You can buy truffle oil--but be careful where you buy it and from whom. Often it is made with other flavouring agents.
Bear in mind also there is a large flavour difference between black and white truffle. The former is very earthy and dark; renaissance writings describe the aroma as being like "unwashed slatterns" and "unaired bedchambers." White truffles are lighter in flavour, with distinct garlicky notes.
If you're using truffle oil, use it only to finish. Cooking with it just doesn't really work. And it is very pungent! A few drops in some homemade mayonnaise would be lovely, or a few drops in some mashed potatoes, yum! Also in scrambled eggs (for that I really would use white, I find black truffle just overpowers eggs completely).
I suggest you to use not the oil, but the butter. I think it's much more pleasurable. I don't know if you can find it where you live, but if you have a chance, go for it.
Another possibility is that you spend the money for a small truffle and put it in oil. If you are passionate about risotto, put it into a small jar with some rice. It will get the flavor and at the same time it will not let it escape, thus wasting it.