Princeton University Library doesn’t collect sets of standards per se, with the exception of our subscription to IEEE Xplore, which does include IEEE standards. We do have an older ASTM collection and indexes. The standards we have are listed in the Main Catalog. We will be happy to obtain any standard that we don’t have via individual request through our Interlibrary Loan service. We will borrow or purchase the standard.
A useful index to standards can be found on the homepage for Engineering Village II, http://www.engineeringvillage2.org/controller/servlet/Controller?EISESSION=1_12bf89211097ae0fe6608ses2&CID=quickSearch&database=1 at the lower left: IHS Standards http://global.ihs.com/?RID=EV2
ISI Thomson Scientific owns TechStreet, another useful index to standards: http://www.techstreet.com/
These 2 commercial services sell standards. You may find standards listed at the web pages of the specific organization, for example: ASME or ASTM, etc. You may be able to buy them for less, directly from the society if you want to purchase any yourself.