If you are looking for printed fabrics, sometime the design you like will be available but not in the material you want. In this case, the supplier should be able to help you in providing printing services in house or know of a company that can screen or digitally print fabric out house. Keep in mind, when printing fabrics (or dying them) there are MOQs for this; be prepared to produce at least 50m+ in most cases. (50m of printed fabric will produce about 45-50 t-shirts). Alternatively, rather than buying fabrics that might not be exactly what you need nor be the print you want, manufacturing the textile right from the factories might be the option for you. Indonesia is one of the worlds largest textile producers and as such is a great source to make not only your own prints but your own fabric weaves as well. There are a number of textile producers in West Java as well as Jakarta - keep in mind again, the MOQ for this would be about 3000kgs (depending on the gsm - grams per square metre - of the fabric this might equate to abut 3500m)
If your garments require accessories such as zippers, fasteners, or buttons, the manufacturer should b able to help you with this. However, a good place to start is at YKK - they are the worlds leader in zippers, snaps, buttons and hooks. You can download the catalogue of all their product from their website.If additional hard ware is required; like the Michael Kors name plate or customised buckle, this might be more difficult to source. These types of items are sometimes made by jewellers as wax moulds or die cuts need to be made. Again, however, ask your manufacturer as they may be able to point you in the right direction to connect you to the right people.