Digital BW, The Print

I'm a real stickler for quality, coming from a large format camera 
background.  I'm planning on purchasing a MF (medium format) camera 
in the near future; I've been seeing some good deals.  BUT, I feel I 
will have a hard time justifying the expense of a 4000 dpi scanner.  
Are there any labs that will scan to that resolution?  If so, how 
much are they getting for a roll of 120 film?  Would it be more 
economical to send them already processed film and just have them 
scan the images that I want?
Thanks,
Randy