I don't know anything about the ValveKing - I got put off by Peavey years ago when they were doing the "Bandit" and "TransTube" thing ... my disdain lingered so I never tried anything new from them - like the ValveKing. Maybe it's great ... I don't know.
Yeah I think a low wattage tube amp is a good route ( the lower the better IMO ). Your budget is more than enough to put a huge selection within your grasp. I checked out the Cornford you mentioned ... never heard of them ... sounded really good. There are SO many awesome amps within your budget that will address your objective it's hard to make a list. One, I think, that is worth checking out is the VHT Special 6 Ultra. (extra gain stage/tube swap options/ NAMM awards, etc)
Have fun with it - let us know what you end up going with (maybe even do a review here?)
Fellow GASser ....