I bought some bitcoin at 26/27/30 and 31k. all profit so far, I am thinking about buying more, but is 35k te expensive to buy bitcoin?
What's your goal? If you're holding for the long term, then the current market hype doesn't matter much. What we're witnessing might just be a temporary market frenzy, and prices could go up or down. No one can guarantee where the price will go, but if you're holding for the long haul, you should be fine.
You bought at 31k, and if you look at it now, that's already an instant profit. But since you're thinking of buying more at a higher price, I assume you're in it for the long term. I'm pretty sure that when the bull run comes, you'll likely enjoy even more profit if you intend to sell. However, as I mentioned, make sure you have a clear goal in mind.