BAT VK-60..New to tubes...Help???

I am looking at a local sale for a original VK-60 with original tubes in mint condition.I want this for a active system to run MIDS ONLY(maybe mid/hi later-passive).I need to know how much it will cost to retube with a warm sounding tube and a fair price for this older amp(1995 I beleive is when they came out???)..Is there different versions?
I will power a dual ATC 75/150S/side active setup crossed at 400hz/3500hz and will need a warm sound.
Any help guys is appreciated.
thanks
NEW TO TUBES
John