An alternative to an all new work wardrobe would be to get stuff for riding to work and then change. Before you say: "I said I didn't want to wear spandex", there's no law that says that what you wear on the bike has to be spandex. Wear something light and well ventilated. The advantage to having a separate set of clothes for work is that you also don't have to worry so much about rain. On cool and dry days you can wear your normal work clothes.

I think sometimes we get so caught up in having to do something a certain way that we forget that there are advantages to being flexible. If you can wear your work clothes to the office 80% of the time without problem then go ahead and do it. That doesn't mean you have to wear your work clothes the other 20% of the time.