Choice of tubes is definitely a personal choice. It all boils down to what sounds best to you. For example, my gear uses 6CG7 or 6N1P tubes. People rave about how great the 6CG7 RCA Clear Tops sound. To me they sound just ok and I prefer my Tong Sol's along with Aprex, Mazda-Brimars and RCA Black Plates.

When rolling tubes there is always a trade off in some part of the sound. You can absolutely go nuts trying to find that right combination. But to answer your question, there is no written rule that you have to have matching price tubes. One of the benefits about tube gear is tube rolling to taylor the sound to your liking.

I hope this helps some.

Larry