Don't fret! A wool-blend suit is ideal, but not a total necessity... I tend to say NO SYNTHETICS not because there aren't great, high-quality suits made of rayon / polyester, etc but because its easy for the first-time-suit-shopper to fall victim to one of the bad apples once they start skipping down Viscose Road. Two of my favorite Nordstrom brands make lovely suits that contain a blend of synthetic fibers...
(polyester / viscose rayon / linen / spandex)
(viscose rayon / polyester / wool / spandex)
Elie Tahari also makes some lovely wool blend suits - slightly pricier, but wool!
And if you like the J.Crew suiting (which is of very good quality, I hear - especially the Super 120s), go to your local store and have a salesperson order several options in different sizes for you - they'll ship straight to the store so you won't have to pay shipping costs and there's no obligation to purchase! I do that all the time with merchandise that isn't available in my local store!