Alfresco University is the only source for official trainings. You may be able to find trainings from other service providers but these will never be quality controlled by a central authority / the vendor and may differ wildly in the depth of the experience. On the other hand, they may offer the benefit of potentially being tailored to your specific use case / requirements whereas the official trainings are all heavily standardised and only deal with the "beaten path".
In terms of "is it worth it" - the question to that certainly depends on your previous qualifications dealing with more complex Java-based business applications. If you have no prior knowledge that amount of money may be well worth it relative to the knowledge being gained. On the other hand, if you already have prior expertise you may be better off with other approaches to learning Alfresco.
