What it costs

Pons launch fee

Read from launchFee() on the Pons factory every time you prepare; at the time of writing it is 0.0005 ETH. The factory insists on the exact amount, so the transaction value equals fee plus opening purchase, nothing more. Deploying the vault and creating the pool cost gas regardless of how much you buy.

Pricing the opening purchase

Launch configuration 0 mints 1,000,000,000 tokens onto a constant-product curve that pretends to hold 1.68 ETH (the phantom reserve). Each extra percent costs a little more than the one before. Buys pay the 1% Pons base fee plus Link's 2% creator tax; the vault is on the snipe-tax exemption list, so the early-block penalty does not apply.

tokens   = supply × bps / 10,000
inputETH = floor(tokens × phantom × 10,000
           / ((supply − tokens) × (10,000 − feeBps))) + 1

Adding one wei after the floor guarantees the curve's own rounded-down output is never short, which is why the launch can demand exactly tokens as its minimum.

These are estimates; the simulation against live state is what decides.

Gas, rejections and reverts

Keep some ETH beyond the displayed total for gas. Declining in your wallet costs nothing. A transaction that reverts launches nothing and buys nothing, yet the gas it burned is gone.