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
mclsound
Only replaced the power tubes once in the 55. I love this amp. I have been driving thiel 2.4s with it. Bass is actually just as good as my old krell. Never thought I would be driving thiels with a tube amp but Victor makes a hell of an amp. I plan to get another to mono them.
BAT amps seem to be very reliable. If you are looking for a warm amp for midrange the vk-55 would be a better choice than the 60. The midrange in this amp is magicical.
Thank you Peter and Rodman for the advice on the 6sn7s. I hope I answered your question John.
There is a vk-55 on the gon right now for $2500 that I would get if I had the cash on hand. I don't due to an ugly recent divorce but you could take advantage of it. I think I paid about $2000 for mine on the gon. You might offer him around that.