Is it a good buy?
I'm currently using a Peavey Bandit 112, that I'm unhappy with to say the least lol.
Plus, I've started rehersing with a band and it's not nearly loud enough.

I was in today trying out the Vavleking, sounded okay, didn't blow me away though.
I didn't really have alot of time to play around with it though, enough to get an idea though.

I was also trying out the new Line 6 spider vavle amps, can't say I'm convinced though, the guys in the shop were saying it's the best amp they've heard in my budget, but as I say, I'm not convinced.

So I'm looking sort've around the £300-400 mark(uk) but 400 is really pushing it, and I can't go used unfortunatly.

I play mostly blues/rock/metal. Like to play alot of Steve Vai and Joe Satriani also.

Any Suiggestions?
They are awesome, I plan to buy one myself if I can get rid of my AVT (which will be impossible). Just play around with the eq for a while, you can get some really nice sounds out of them.
I think the best value is the 112, especially if you are going to mod it later. Me I'm perfectly happy with mine stock.
if you wait more then 15 minutes or 8 minutes before your posts

maybe someone would have seen it down lower.

have you looked at the valve king thread?
First of all, don't bump this 3 times within an hour.

Second, with that budget you can do better than the valveking. I am not sure about UK prices so I can't really recommend anything, but someone in here can.

Btw, you can get the 112 version and change the stock tubes and speaker and it is a totally different monster. Much much better.
Noticed your username thing is sdmf somethingorrather, if you are looking for a sound similar to Zakk Wyldes you might want to look at something else.