I think it all depends.
Not saying the course is not good ah...but remember, it's a 'home-study' course which means you have to read course materials, understand, go and apply, then feed-back results to 'lecturer' to comment and make suggestions. This works very well for some people.
If you're an organised and focused sort of person, you could consider gathering and structuring your own research materials, project assignments, research in bookshops/internet, absorb, apply and post up in various forums for both technical as well as artistic critique. Cost? Electricity, time and perhaps printing/ink costs if you print out articles.
Of course, in the old days, NYIP would send you physical materials like negatives and such for you to practise your darkroom work, printing etc. I suppose now they would be e-mailing or sending CDs, especially for digital darkroom work.
Whether cost is worth it to you all depends on the quality of their course materials, any programmes/applications/digital goodies etc. Another consideration could be whether you're comfortable discussing things with Ang Mors via electronic means. I notice that some Asians, who are very talented, have major problems learning from American or European forums and discussions because Ang Mor speak/write the more powderful England and there may possibly be some cultural differences that could invariably influence the discussions, or at least the language they use in terms of examples, analogies and artistic influences.
I'm sure others who have gone through correspondence courses are in a better position to comment and advise.
Not sure how good they are though.
