Need Pump for my Disco-help

Hi Members,
I need advice from experienced members on which pump to use for my Disco.
I can get a new Hill MK4 for $260. I don't see any used ones. I can get a used twice MK3 for $125 shipped. 
How would you all advise me. Which way should I go if I want quality, easier to pump and last longer with good support. 

I am currently using a Benjamin pump.

Thanks for any responses.
Vic