Price per thousand is the wrong comparison on its own. Three terms decide what a credit actually buys: whether unknown results consume one, whether duplicates are charged, and whether the balance expires. A cheap credit spent on an address the engine could not judge costs more per usable answer than a dearer one that is never spent that way.
Expiry is where the industry divides. Kickbox and Hunter both expire credits at twelve months. Bouncer, Reoon, Emailable and others do not, and charging for a balance you then delete increasingly reads as a legacy practice rather than a pricing decision.
Not charging for unknowns has become table stakes among the vendors worth considering, and for a good reason. Billing for an address the engine declined to judge means charging for the work it could not do.
Subscriptions suit continuous verification at a signup form, where volume is steady and predictable. Pay-as-you-go suits list cleaning, which is lumpy by nature, and paying monthly for a list you verify quarterly is a straightforward loss.
ZapBounce prices pay-as-you-go: $5 for 1,000, $25 for 10,000, $89 for 50,000, $139 for 100,000, $549 for 500,000 and $949 for 1,000,000. Credits never expire, and neither unknowns nor duplicates consume one. The free tier is 100 credits a month, recurring, with no card.
Pricing a 56,000-row cleanup
Say your export has 56,000 rows. After repeats are collapsed, 49,500 distinct addresses remain. Of those, 3,000 come back unknown. On our terms neither repeats nor unknowns use a credit, so the job spends 46,500. The 50,000 pack at $89 covers it, and the 3,500 credits left over never expire, so they'll still be there for next quarter's cleanup.
Run the same file under stricter terms. If every row were billed, you'd need 56,000 credits, which is past the 50,000 pack and into the next size up. On our own price list that's the 100,000 pack at $139. The file didn't change. Only the terms did, and the bill rose by more than half.
For scale, the low end of the older vendors' range is $0.004 an address. At that rate, 56,000 billed rows come to $224.
Price per usable answer, and when price doesn't matter
The number worth comparing is what you pay for each answer you can act on. Say a vendor charges $0.001 an address, bills for unknowns, and returns a fifth of your list as unknown. You paid for 10,000 checks and got 8,000 answers, so each usable answer cost $0.00125. The sticker price understated the real one by a quarter.
Set the bill next to what your email platform charges as well. Most platforms price by contact count, so dead addresses carry a monthly fee for as long as they sit there. A one-time cleanup often pays for itself within a few billing cycles on storage alone.
For very small needs, price shouldn't enter into it. If you check a handful of new contacts each week, a free monthly allowance covers you. Ours is 100 checks a month with no card. Spend your attention on how the vendor labels what it can't resolve, because that choice affects every list you'll ever run.
Related questions
What is a fair price per thousand addresses?
Between $2.50 and $8 per thousand at small volumes, falling below $1.50 above 100,000. Anything above $10 is paying for brand rather than checking.
Should I buy credits or a subscription?
Pay-as-you-go for periodic list cleaning, subscription for continuous signup-form verification where volume is predictable.
Do verification credits expire?
With some vendors, at twelve months. Ours do not, which removes the pressure to buy only what you will use this year.
Is the cheapest option good enough?
Price does not predict quality in this market. Ask about the unknown share instead, since that is what a low price sometimes hides.