Not sure what you mean by cheapest. Wallets are free, beyond the ~3xlm needed to open some trustlines. But just get a wallet with one of the sites or app i mentioned, create a stellar wallet and then fund it with xlm from your counbase account. Need 500 xlm minimum mived into the wallet you create to get the airdrop and uou need to buy 1 aqua from the exchange on the wallet as well