Hmmm, I sent off an e-mail asking 3D World magazine why the difference in the subscription rate I was charged.  Here's their answer...

*Prices are set by the Publishers throughout the year. There are special offers
available at various rates advertised both within the magazine and online. Some
subscription promotions feature a discounted rate and others advertise at the
standard rate.  To qualify for the discount, the source promotional code must be
applied at the point of order.

I am sorry you have seen an offer which you prefer, however, I am unable to
refund the difference against the original offer under which you subscribed.

Soo, buyer beware - if they send you a notice to re-subscribe, throw it away since it will have the highest price.  Great customer service.  This is the last subscription I will get from any of their magazines. 

Peggy

LVS - Where Learning is Fun!  
http://www.lvsonline.com/index.html