[hardy-l] What do these books have in common ?

[Fraser Pakes]

Quick now . . . what do these books have in common ?

Achievement of Thomas Hardy (Mallett)
A Companion to Thomas Hardy (Wilson)
The Expressive Eye . . .Work of Thomas Hardy (Bullen)
Palgrave Advances in Thomas Hardy Studies (Mallett)
Reading Thomas Hardy {Pettit}
The Secret Life of Thomas Hardy (Neill)
Thomas Hardy Texts and Contexts (Mallett)
Thomas Hardy's Novel Universes (Gossin)
Thomas Hardy's Public Voice (Millgate)
Thomas Hardy A Textual Study (Ray)

Answer - high price - they all will cost the purchaser over $100 each  
(some well over $100.)
My next question is - why ?  What has made Hardy studies become so  
expensive in the last few years ?
Is it because the market for such books is so limited that the  
publishing costs have to be high ? I wonder if Hardy would have been  
flattered by all this ?