Does anyone know of inexpensive "origin pull" CDN service providers.
The only provider that I've found that provides this are SimpleCDN and Akamai. Akamai is crazy expensive and SimpleCDN seems to change their business model daily, so I'm concerned with using them.
I've used LimeLight with an origin pull model and it works quite well. The only issue is their edge network is constantly expanding so if you want to employ any kind of security for your content on the origin (i.e. firewall ACL's) it becomes a constant maintenance PITA. OTOH, if your content if wide open to the public then I would highly recommend them.
I don't know how cheap they are for a new customer. I guess it depends on how much traffic you are expecting (and ultimately how much money you will give them). My company does a fair amount of CDN business so we got really nice pricing, but YMMV.
Also, if you are a Rackspace customer you might be able to leverage their pricing - they use LL exclusively for their own content and for their cloud offerings (http://www.rackspacecloud.com/cloud_hosting_products/files).
Good Luck!
We use PantherExpress in "pull mode" (not sure they do anything else, really) and it's great. Also very competitively priced. They're now owned by CDNetworks; I haven't talked to their sales people at all so I don't know how much changed.
LimeLight were also much better priced than I expected when we were getting quotes; but they had this stupid "oh, a little more for this feature and extra for that feature" pricing where PE just gave me a simple price including all their features.
When we were evaluating EdgeCast was missing some of the features we needed, but I think they've caught up now.
We use 10-20Mbit/sec on the CDN to give you a ballpark.