I'd say they are worth around a grand each, anything less and you have yourself a bargain, amp buyers.
Basically, I have a strong interest in them reaching high prices, which isn't entirely beneficial to the basschat community of people who like playing nice amps. Those mullards represent a lot of value independent of the amp, if you want money, sell those separately, and stick some Shuguangs in there, and you still have yourself a fine working amp. One of mine, fixed up and working, I would want more than £400 for, and that would be without mullards (modern valves though, and all new parts, bulletproofed for gigging purposes). I probably wouldn't get that for them, but I'm cheerful to sit on them and wait till I can. I got a little over 400 for the working but not ideal one I sold previously, international shipping is what really pushes up the value.