Let's see, I generally have a uniform for each season. Summer consists of polo shirt or lightweight washed oxford style shirts with slimmer Bermuda style shorts. Fall is usually a lightweight cotton sweater with jeans. Lambswool or merino wool sweaters with jeans or corduroys for winter. Layer in the occasional oxford style shirt in a normal weight cotton. Spring is sort of a toss up, I wear whatever the bi-polar Maryland weather allows that day. Light sweater, washed button down shirt, jeans or omitting the first item if it's warm enough. Casual New Balance shoes usually fit the bill in all seasons.
So all in all I probably own about 50 pieces and I back fill items as they wear out. I also pick up items for special occasions a few times a year as most do and shop enticing sales here and there, but for the most part I buy the best quality I can afford and wear my clothes out before replacing them.
Polo shirts and lightweight shirts are my biggest quantity pieces. Summertime and sweat causes those to wear out pretty fast. Sweaters and jeans last me years. I also own one winter jacket and one spring jacket for rainy days and that's it.