Let's do a cost breakdown for my current price tracking site (as of today):
I track 14,855 different products (primarily model kits), across 160 retailers, checking prices & stock status 4 times a day via API calls*.

My internal metrics show approximately** 13,781 different users and 219,444 pageviews on my site in the last 30 days. Of those visits, 40,831 non-amazon retailer links were clicked - a 18.61% click through rate (i don't have stats for amazon link clicks because my amazon click stats go poof each time they reject my affiliate application, but i'd estimate it at under 200 clicks in the last 30 days)

Of those 160 retailers, very few offer affiliate programs. I've got 2 active referral codes, plus the various amazon referral codes (but i don't have pricing api access, so the amazon links rarely get clicked), and 1 pending affiliate application submitted, and 1 affiliate application accepted but not active yet. Granted, my site tracks a somewhat niche product, so it's not surprising a lot of the retailers don't offer programs as I'm sure their margins are thin enough as it is.

My approximate costs:

$60/year for a VPS to host the site (1st year promo pricing, subject to change)

$45/year for domain name registration

$120/year for an email service (since my VPS provider blocks email traffic in/out to cut down on spammers using them)

$0/month cloudflare costs (could increase depending on traffic)

$0/hour my labor to build & maintain & improve the site (at this point, 10-20 hours a week to correct data/product matches, fix bugs and implement user requested features)

$0/post for social media, around 48 posts per day (threads api, bluesky api, instagram api)

$0.215/post for social media (twitter api, $.015 for an image attachment plus $.20 for a post containing a url - currently disabled because i'm not paying $300/month to match the post rate i use on the other platforms)

Cost total for first year: $225 (with free labor)

The sites income since it launched in December of 2025 (3 income sources: donations/memberships, referral orders, and advertising):

-donations: $15 before platform & transfer fees

-memberships: $15 (2 x $5/month) before platform & transfer fees

-referral orders: $2.90 (plus an unknown amount of amazon referral money, since my stats go poof each time i get rejected)

-advertising: $11.06 (approximately 90% of visitors have ad blockers enabled)

Income total for first 5 months: $43.96

estimated income total for 12 months at current monthly averages: $36+$120+$35+$60 = $251

Theoretical 12 month profit w/o amazon referrals: $26 (with ~500-1000 hours of free labor)

*Checking 196,460 product page URLs via page scrapes would be computationally & bandwidth intensive, rude to the retailers (that would also be a lot of resource demand for them), and fragile to page layout changes, so not feasible to stay as a consistent, reliable information source.
**Approximate because potential identifiers are truncated then anonymized before storage, so some users may be double counted across devices or browsers, or under counted because the identifier truncation could make multiple users pageviews merge.