I wouldn't buy one of the cheap amps. You should look for a solid power supply with lots of filtering. You want very clean power feeding the tubes. This is where the discount amps usually cheap out. People don't pay attention to the power supply - they mostly care about how cool the case looks and how much tuberolling you can do. I'd rather have one or two tube possibilites and clean B+ in the circuit.
Second, avoid tubes on PCBs if at all possible. PCBs are better suited towards solid state and lower operating temperatures, unless they have adequate heatsinking. Most solid state amps get the heatsinks right, but it is not easy to heatsink a tube. Further, if the tube sockets are mounted on a PCB, inserting and removing tubes will cause the PCB to flex. This can cause solder joints to crack or pull up a solder pad on the board. Couple that with a lot of heat and you can get a mechanical failure. Repairing a PCB can be tricky, especially if a pad lifts. If you want a really solid tube amp, buy one that's built point-to-point. Point-to-point won't fail that way and is far easier to repair, if needed.
