The $50 wasn't per-takedown, but per-incorrectly-filed takedown. Not sending a link to the proper (likely free) method is a dick move, but I doubt it breaks any laws.
The DMCA is the US explicitly states that ISPs and hosting companies must accept the burden of any costs associated with DMCA requests, but this is not universal. Consider that in New Zealand, a rights holder can expect a fee of up to $25 for the host to recover costs related to processing a takedown request (
http://www.med.govt.nz/business/inte...hts-owners.pdf if you'd like to read it).
Coming from a carrier background, the costs of handling these takedown requests aren't trivial, but failure to handle them (as a USA-based company) can result in the loss of common carrier status. Similarly, a company in another country needs to be very careful to follow their local laws to maintain that equivalent status, if you lose common carrier status you simply cannot exist as a host or ISP. Those guys may be opening themselves up to problems for accepting a DMCA request regardless of circumstance or payment...