Is it common for tubes to outweigh the cost of the amp or preamp?


I just got my first tube (headphone) amp and was wondering if it is common to spend more on the tubes than the actual cost of the amp. The amp was $599 with stock tubes. I just ordered NOS driver tubes that ran $640 for the pair and the power tube upgrade I'm planning will be another $300. That has the tubes sitting at 1.5 times the cost of the amp itself.

I don't find the total of $1539 for the amp and upgraded tubes unreasonable but considering the next model (amp) up is $1199, it has me wondering what would be better... a lower cost amp with superior tubes or a higher cost amp with stock tubes?
samiamnot
@testpilot 

300B tubes can often exceed the cost of the amp.  
WOW! You aren't kidding. The manufacturer of my amp has a pair for $2k, FOR THE PAIR! Insanity. I'm feeling like I got off easy now.
Good to hear that you are enjoying your purchase.  At the end of the day, that's all that matters.
Thoroughly enjoyed. But now wondering what these tubes will cost in 2050. I've got another 40 years of listening left in me. Longer if I download my brain into a robot.
When I bought my grey shield/plate, early Sixties, Siemens, they were just over $250 a pair(average). My CDP takes six, in it’s analog section. The player’s original cost was just under $5000, so I wasn’t upside down. The diff was remarkable, so- I bought six more, for spares. After about ten years, I thought I might compare the spares to the used. No apparent/appreciable difference (boy, was I glad!). I’m hoping the CDP will outlive me. You apparently enjoy the clean, wide open, extended sound of the CCa’s. If you’re ever in the market for 6SN7 types, the bottom gettered, 1940’s era, Sylvanias and Ken-Rads, offer the same presentation and are very close to the performance of such as the Tung-Sol round plate, or Sylvania 6SN7W(tall bottle/metal base). Much less expensive than them, too. 
Just for anyone who is interested, there is a difference between shields and plates. All Siemens 6922/E88CC have gray plates. They made a chrome plate 12AU7 and you can’t mistake these, but as far as I know they never made chrome plate 6922s.

What the gray shields are are two vertical strips located beneath the getter supports where the supports attach to the top mica. The gray shields look just like the gray plates.

Siemens 6922/E88CC made after 1964 or 65 or so have silver shields and gray plates. A silver shield can be seen on the tube on the left in the picture in this ad from ebay. The M in Siemens is printed right over the top of the silver shield.

https://www.ebay.com/itm/E88CC-CCa-6922-6DJ8-Siemens-Matched-PAIR-NEW-NOS-SILVER-SHIELD-Strong-/182403712807

Why care? Back when I was buying tubes it was said that the gray shields were a far superior tube to the silver shields. The silver shields were described as being bright and sounded terrible compared to the gray shields. Even CCas come with either gray or silver shields.

Opinions change as stocks of the most desirable tubes disappear, though. Silver shields may be considered good quality tubes now. I don’t know. Anyway, if you’re buying Siemens 6922s you should know that there’s a difference between gray and silver shields.