It really depends on what you're looking for and if you know how to find it. For example--I'm a hunter on ebay (still). I have very specific items I'm looking for from specific brands. I'm willing to buy used, but only if the item looks, feels, (smells) brand new--so I ask a LOT of questions. Consequently, last week I scored a Ralph Lauren purple label silk shirt for $0.99 because no one else bid on it. Came in yesterday...it looks like I removed the tags myself. Brand new. With that in mind, you can go for nearly any designer if you know where (and how) to look. Sign up for websites with deals like Haute Look and Gilt (free to sign up). Still...you asked for brands, so here are many:
Sweaters: Brooks Brothers...Lands End (their 2-ply cashmere sweaters are heavenly)...Neiman Marcus...Loro Piano (very pricey though)
Button-down shirts: I DO like Calvin Klein for a more casual look...I also like Michael Kors, Perry Ellis, and Geoffrey Beene as they fit me well...Ermenegildo Zegna...Gant...Thomas Pink...Zachary Prell
Polos: Bobby Jones has become my favorite brand of polos. Tons of styles. Very soft. Not a lot of people wearing them...Fred Perry...Original Penguin...pricier ones like Lacoste and Burberry
Jeans: I own a pair of 7 For All Mankinds, Hudsons, AGs, and Armani Jeans. Lucky Brands are also nice. Most Hudsons are a lower rise (which I don't like), but I found a pair with a more comfortable rise, and I tell you what...when I'm wearing Hudsons, I never want to take them off. They're like sweatpant-comfortable.
Casual pants: I stick with Dockers. Why mess with anything else?
Dress pants: Austin Reed...Calvin Klein...Diesel...Hickey Freeman...Mossimo...again, I like how Perry Ellis and Geoffrey Beene feel/fit on me.
Obviously, you can't go wrong with anything by Gucci, Dolce & Gabbana, Giorgio Armani, etc, but they all come with the price tag you're looking to avoid.