As martinuzz mentioned, 'Business Casual' means different things to different employers. If you don't know, and are unable to find out before shopping, a new/prospective employer's take on business casual, you're probably better off playing it safe with more conservative color/style choices (but of course if you DO know what is normal at the workplace in question, be consistent with that). In going with a conservative color scheme, khakis or grey/charcoal slacks are probably a good choice to go with the selection of shirts/shoes you already possess, and almost always accepted as within the realm of business casual. Some places will allow black (but not blue) jeans in business casual attire, but avoid them if possible unless you know they are acceptable at the workplace where you will be. I'd try hard to avoid spending the money on custom tailoring unless you are certain that slacks are going to be needed in order to fit into the business culture where you'll be, and you really can't find any that fit otherwise. You might try searching out specialty stores that cater to tall people, for a price point above what you'll pay in other stores, but still less than quality custom tailoring. Many cities in the USA have such shops, but what options are available will vary quite a bit from one place to another, so I can't make specific suggestions there.