The users of CL never agreed to let you copy their postings to whatever website you feel like, also it is against their TOS to do so:
Any copying, aggregation, display, distribution, performance or derivative use of craigslist or any content posted on craigslist whether done directly or through intermediaries (including but not limited to by means of spiders, robots, crawlers, scrapers, framing, iframes or RSS feeds) is prohibited. As a limited exception, general purpose Internet search engines and noncommercial public archives will be entitled to access craigslist without individual written agreements executed with CL that specifically authorize an exception to this prohibition if, in all cases and individual instances: (a) they provide a direct hyperlink to the relevant craigslist website, service, forum or content; (b) they access craigslist from a stable IP address using an easily identifiable agent; and (c) they comply with CL's robots.txt file; provided however, that CL may terminate this limited exception as to any search engine or public archive (or any person or entity relying on this provision to access craigslist without their own written agreement executed with CL), at any time and in its sole discretion, upon written notice, including, without limitation, by email notice.