Kotare,
I do think it's important to supplement when you are TTc. Yes it does get expensive but I believe it's almost impossible to get all of our dietary needs from the foods we eat. Our soil in Australia is depleted in a number of important nutrients (Selenium and Zinc are high on that list and essential for ttc). Iodine is another element that is being found to be depleted in many women.

For me a supplement is a bit like an insurance policy. I try to eat really well ( I personally follow an "almost" organic diet) however, I don't always eat as well as I should... Folic acid has been found to be very important for pregnant and ttc women. Not just for the help it gives to the developing neural tube but also for its affect on dna. Folic acid should always be taken with b6 and b12 for the best affect though.
It is my belief that your partner should also take the same. It takes an ovum and a sperm to make a baby so both parts need to be healthy (I believe!)
Good luck with you journey may a be yours very soon...