The cost of Fantasy Grounds is two-fold. In terms of the program itself, it's cheap for what it gives you, honestly. I've been playing D&D and it's relatives for decades now, and after running a campaign in Fantasy Grounds for the past year I can tell you unreservedly that I would hate to go back to playing without it. The tools are robust, but they do require some experience to use to their potential. While it is possible to buy the software and some content and start running a game immediately, the truth is that you're not going to be very good at it until you gain a level of familiarity with the quirks of the program. It's not difficult, and it will only take a few sessions to get it down.
The second issue, though, is the cost of the content. When I first started using Fantasy Grounds, my group was playing Pathfinder. I bought the program and that's it. The Pathfinder content we were using was not as fully featured as the 5e content we're using now, but it didn't require re-purchasing the books. We created our characters in PCGen (for free.) A lot of stuff (feats, for example) we copy/pasted from the pfsrd, but it was easy to do. 5e is a completely different story.
Since there is no easy way to get the 5e content as clean text, you can't just copy/paste it into your character sheet. That leaves you with two real options: put together your own content module from a scanned document, or buy the WotC licensed stuff. The official content modules are pretty great, since they're produced by SmiteWorks and updated with corrections and additions. There is an ongoing effort to constantly improve these content modules as tools in addition to the content from the books, with automation built in to spells and class mechanics and stuff. They are incredibly useful game tools, that are getting better all the time based on user feedback. They're also outrageously expensive, especially if you've already paid for the content in the form of a hardcover.
The problem as I see it is the adventurer's league strategy at Wizards of the Cost. They clearly believe that facilitating "organised play" at a "FLGS" (f***ing local gaming store) is the key to the success of the D&D brand. I find that belief questionable, but presumably Wiz has more data than I do. Apparently the gaming store business model depends very heavily on selling overpriced books. I mean, I get that the Amazon price might be too low to match, but when you're charging twice the Amazon price, you're only selling to suckers and chumps. Maybe if a gaming store could find a reasonable price point they might start selling books to me--just sayin'. In any event, the perceived need to support the game store economics leads to WotC setting their MSRP at an unrealistic level and, apparently, prohibiting Smite Works from selling licensed D&D products at the price you might expect to pay for a digital product.
It would be reasonable to get the Fantasy Grounds module as an add-on to your hardcover order. Amazon is certainly set up to deliver a digital code along with the purchase of a physical product, it's not a heavy lift. The problem, I'm guessing, is that while Wizards doesn't want to lose out on book sales through Amazon, they also feel like they are beholden to these f***ing local gaming stores that are the gatekeepers of the Adventurer's League organised play stuff. WotC has been unequivocally incompetent when it comes to a digital product strategy for several years now, and I think the fear of offending the gaming stores is part of their problem in that regard.
I suppose the WotC beliefs are also based on their sales campaign for another game that involves gathering a bunch of magic cards.