It's a big ripoff here. Simple as that.
I get my tubes from ebay, a local seller here in Victoria. I think the guys username is vicmaz on ebay. Top service and good prices. Very easy going guy. I bought =C= EL34's and no issues whatsoever. Told him to match for my recto. I can't remember what rating colour I decided to go with, I think it was 'green'.
I've also bought preamp tubes off ebay and from the US. Preamp tubes are just plug and play so I wouldn't worry about these so much. You can just about use any brand and type you want (see paragraph below for caution). It's the power tubes you need a little more care with. If the power tubes run too hot, you could be in a bit of trouble. Just make sure the supplier matches all of them and are all in the correct range.
Another thing to look out for is the preamp tubes position. Something about cathode follower for V3 and V4. Some brand preamp tubes will fail prematurely and it sounds like this is what is happening to you. I think the Chinese made and JJ's are good in this position. EH, Tungsol and a couple of others are not recommended in these positions. Scoll halfway down this page http://forum.grailtone.com/viewtopic.php?f=24&t=55858
Do further search on this site with terms like 'cathode follower' in the search field.