Go for Used
I did my first sprint-distance triathlon last year on a used 1990 Bianchi Volpe. It has "male dimensions" for the frame and I am female. Though, I have a long torso. Many woman do not.
I opted for a used bike 'cause I didn't want to invest too much in an event I've never tried before. Luckily, I loved the triathlon and I hope to upgrade soon to a faster used bike or a modestly-priced new bike for future triathlons.
You may wish to get used bikes, in case triathlon isn't you or your wife's cup of tea. I suggest checking on Ebay sales in your area or your local Craig's List. As you probably know, dealing locally often allows you to pick up the bike and avoid any shipping costs. Good luck.