Markup
Markup is the difference between what a reseller pays its provider for an order and what it charges its own customer, set per service or as a catalogue-wide rule.
A reseller imports a service list from its provider and receives each service's upstream rate. Markup is what it adds on top. Two methods are common: typing a price by hand on each service, or telling the panel to apply a rule, such as adding a set share to every imported rate, and letting it price the whole catalogue in one pass. A rule is quick across hundreds of services. Hand-set prices let you carry more margin on the services you can deliver reliably and less on the ones you list only to look complete.
Upstream rates are not fixed, and that is where a hand-typed price goes wrong. A provider can raise a rate without notice, and a hand-typed price stays where you left it. Some panels keep imported prices in sync with the provider, or offer it as a setting; where that is off, or absent, nothing moves your price for you. From that moment every order on that service is sold below what it costs you, and nothing in the software refuses an order for having a negative margin. Pricing by rule catches the move when the list is re-imported, but only if someone re-imports it. Compare your own prices against the current upstream rates on a schedule, and after any stretch when you were not watching.
Markup also has to cover more than profit. Payment processing takes a share of every deposit, refills and refunds are delivered at your cost, and support time on stuck orders is unpaid. On the buying side, the same arithmetic explains price gaps between panels selling identical supply: each step down a chain adds another margin to the same order.
Price is not profit
Markup and profit are not the same, and a higher price does not mean a worse deal. What you pay reflects how many resellers sit between you and the supplier and what each of them spends on fees, refills and support. A thin markup applied four times over can cost more than a wide one applied once.