While the best items you can buy are custom-made or fine clothing brands previously mentioned, there are many others that qualitatively can be nearly as good if you pay attention. We'll start with shirts and sweaters. The store brands of Saks Fifth Avenue and Neiman Marcus are consistently excellent, on par with the best designer brands, apart from exceptional firms like Luigi Borelli, where shirts are hand-made with mother-of-pearl buttons. These stores carry shirts that are Italian-made. along with other garments that are of top quality. under their store labels . Bloomingdales, which has faded somewhat, Barney's, and Nordstom are also good, but you have to look at the label to be sure where the item is made, as they have started to carry some cheaper goods that are not the same quality. You can find things at Macy's if you shop with careful discrimination. They carry clothing from Tasso Elba which is quite good, along with his excellent sweaters. You can also get a good product from the British shirt company Charles Tyrrwhit. When it comes to low-price bargains you can't do better than JC Penney, where custom monograms are provided on their serviceable Stafford brand at half the price everyone else charges.
Suits, sports jackets, pants, and overcoats are all over the map, ranging from very cheap to very expensive. Generally you get what you pay for, apart from coutoure and inflated designer brands. Fit, of course, is paramount, but otherwise the first thing to look for is fiber content. You want to stick with natural fibers like wool and avoid synthetics. A cheap polyester suit is going to look like one, and unsurprisingly will originate from somewhere like Pakistan or China. Blends are acceptable if the natural fiber predominates, particularly in pants, where they can reduce wrinkling. The second thing, as previously noted, is where the item is made. Again clothing from Italy, followed by some other European countries, the US, and Canada (i.e. Jack Victor) is superior. The third thing is a don't-do. Don't choose by designer name unless it is from one the best, previously mentioned, who don't make multiple lines of varying quality. Too many are now less than trustworthy when it comes to mass produced goods. For example, I would completely avoid anything by Calvin Klein or Ralph Lauren these days as stores are flush with cheapie good carrying their name.
That doesn't mean you have to spend a small fortune to dress well. There are men's clothing stores with an acceptable line of suits, such as Joseph A. Bank, whose apparel runs on the conservative side, where there are frequent sales. Brooks Brothers is a step up, again mostly traditional and and ideal for business. Some designers produce some surprisingly good middle-priced suits and other apparel, such as Pierre Cardin, who ironically was the first one to license his name on everything and thereby diminish it, but there are still appealing designs under his brand. Other firms in this category include Adolfo, Daniel Cremieux, Geoffrey Beene,Valentino and some others. I would avoid the "brand" of anyone who is not a bona fide designer and knows nothing about tailoring.
There is one way you can sometimes purchase high end clothing for a low price, within limits, on Ebay. Ideally look for something labeled NWT (new with tags) because it can usually mean that someone bought something that doesn't fit right, or their wife bought it and they don't like it, or it is part of a discounted lot. Occasionally you can find something with minor imperfections. Just be sure to be completely informed on any of them and ascertain whether they are visible. Another variation is NWOT (new without tags), for which you should check the reputation of the seller. There is also used, provided it is specified as being in excellent condition, hardly worn, etc. Be sure the seller accepts returns, has a high rating, and that there is a thorough, detailed description. Measurements should be provided, which you should check carefully to match your own. This is at best, an occasional way of doing things, since whatever is was selected by someone else, and generally you should otherwise buy something new that is completely suitable for you and within your budget.
Thus things to look for are the fit (more on that subsequently), the material, where the item is made, what firm it is from, and whether the cost is reasonable. Lesser known designers can sometimes make fine goods, while big names can produce mediocre products, so don't worry too much about labels. No one is going to see them. Instead look for the best material you can afford, the most elegantly finished product, and what is most suitable for your circumstances.