I don't purchase new clothing/accessories specifically for vacation, but I will purchase things I need. If I purchase anything at all for WDW trips, it's usually a new pair of sneakers a month or two before the trip so I know they will be comfortable! Sometimes a new pair of walking sandals, as I wear those throughout the year at home. My style is business casual (yes, even in the parks!), so I wear the same clothing that I know is comfortable for a sixteen-hour workday at home on vacation! 
If I have to travel to colder climates for business or pleasure, I usually have to purchase some items. I live in the desert and the warmest clothing I own are a reversible fleece/water repellent stadium coat and sneakers! Not really suitable for climates with extended temperatures below 40 degrees! Particularly for a desert rat who considers 60 degrees to be *on the nippy side*!

If I have to travel to colder climates for business or pleasure, I usually have to purchase some items. I live in the desert and the warmest clothing I own are a reversible fleece/water repellent stadium coat and sneakers! Not really suitable for climates with extended temperatures below 40 degrees! Particularly for a desert rat who considers 60 degrees to be *on the nippy side*!
On our last trip, he ruined his shoes the WEEK before we left and I bought him a new pair and BEGGED him to break them in before we went. He didn't and we spent the entire week sitting on benches because he had horrible blisters. GRRR. This will NOT happen this time! 