Yeah, but it isn't even remotely enough and the majority of what has already been pledged are from the hype wave of HN that will disappear in a day or two. You only get the hype wave once.
What data are you basing this off of? Have you ever tried selling products at significantly different prices and measuring revenue/profit? I have-as one example, I've sold the same PDFs at $.99, $9.99, and $49.99. The $.99 and $9.99 price points got about the same revenue, with $9.99 getting much higher profit due to transaction costs. But $49.99 got much, much more revenue and profit than either of the lower-priced options. And I've seen this over and over again, with a variety of products.
What you said is confirmation of my guessing. I'm saying if $50 includes beta (currently only $100 [EDIT: just saw $50 for beta added, thanks for listening to HNers ibdnox! Oh, wait, that access is much later than the $100 price point..]), then the amount he may be getting may be higher than the current amount.
FYI, no data to base off, just guessing, hence the words "think", "would" in my post you're replying to.
Of course it isn't a bad start. But, as others pointed out, the price point is pretty high as it is merely a bet on the product.
I myself would have considered buying/donating, although I wouldn't use the first version (not doing any Javascript or Clojure projects). But I see value in what is planned here and would be willing to bet twenty or even thirty dollars on its success. It would be a bet that the final product, which I basically bought, is good enough that people implement plugins for it that I could use (ruby/php/java/actionscript/etc).
But $50 is a pretty high bet in this case, and I would bet that I am not the only one in the described situation...