What is man?
What is money?
Does man have a soul, and if so, should I put it in this $12 adventure?
This thread's going to some weird places, man.
The other factor, is as EOTB said, "Will I truly use this?" or am I just looking to be inspired---if the former is true, acceptable cost is probably doubled.
Soft disagree. If your groceries suddenly doubled in price, would your trips to the grocery store be more or less frequent? Would you more or less inclined to add additional things to your grocery cart? And what if a store opened nearby with slightly different products at normal, undoubled prices - would you even look at the old double-priced store again? Remember that you will "truly use" your food.
People are hardwired to look at cost first, that's why those little tricks like ending prices in ".99" exist. Adventures are (mostly) sold impulse buys at a good price - I don't have the metrics, but I'd wager money that far more adventures are moved when bundled into some deal than when standing alone. Fortunately (or unfortunately, depending), you can trick a human mind into believing that a normally-priced thing is a bargain - sales, and bundles, and scarcity and whatnot. But those tricks only work if the potential customer is already looking at the product. I don't mean already already
considering it, I mean they have to literally
learn of the existence of the product before it will be sold to them. That's where most adventures struggle - advertising. How many modules didn't hit it big until the reviewers sunk their teeth into it? How many adventures have you personally discovered because someone other than the author told you about it? Most, I'd wager.
DMs are, by their nature as the lone leader and module-purchaser for an isolated group of players, poor advocates for a product. There's no cross-pollination of sales either - quite the opposite, really. If someone has already played through an adventure with a different group, then their current group will be unlikely to run it (unlike with normal products, where previous usage makes it
more likely to convert other sales). Likewise if the DM changes groups, he's not going to re-buy the adventure for the new group. Modules are not consumables - once they're out there, the customer isn't coming back. What that means is that for every sale you make, you have to start from scratch for the next customer. There's little carry-through.
There are more big obstacles with the adventure-writing business, from a marketing perspective:
1) people are largely unaware of what's out there (advertising is expensive and tough);
2) the customer pool is pretty small (DMs who coincidentally run the same system are the only ones buying your modules);
3) product endorsement by word-of-mouth is stifled because potential buyers don't intermingle as much (groups are isolated); and
4) there's no centralized repository as an audience interface (there's no D&D-TV channel to run ads on, no BoardGameGeek.com equivalence for D&D).
It's bleak, but not impossible. Obstacle 1 requires a knowledge of the best advertising routes and practices to reach the audience. Obstacle 2 is circumvented by making the module appeal to more customers (this is the origin of the pervasive modules-as-reading-material trend) and by writing for the most popular system (mainstream D&D). Obstacle 3 requires endorsements by well-respected industry individuals with large audiences (If Matt Mercer says "buy this thing", you better believe those sales are going up). Obstacle 4 requires focused, targeted advertising strategy across multiple channels to maximize what we in the biz call "impressions".
Despite your personal feelings about advertising/marketing, it does have its uses. In a market where most are ignorant of the product and hesitant to part with their money, it becomes all the more important.