I think your best bet is to have an account with a centralized exchange, and then doing limit orders to get maker fees. That’s the cheap part. Getting it off the exchange is the expensive part with those amounts. I know that some exchanges support Lightning, and I think on some of them Lightning withdrawals are currently free.

Opening a channel to a self-custodial wallet can get expensive, but if you’re running a node it’s probably not that bad.

In Europe you can use Relai (EUR/CHF) with a 1.5% fee for Bank Transfer and once per month <100 EUR/CHF are free!

Also you don’t need KYC for smaller investments (though they know your name because of your IBAN)

The best part: external wallets are supported!! And soon lightning ⚡️

River or swan.

I use Swan with automatic weekly DCA and auto withdrawals to cold storage.

Get $10 in $btc with my referral!

https://www.swanbitcoin.com/tennessee-stacker/

Also Cashapp = relatively low fees.

Swan is good platform to use , 0.99% fee paid upfront and no fee to send to cold storage

River likes their fees… makes me not use them hardly anymore

Robosats and just live with the premium

#Strike is one of the most cost efficient for stacking that amount at least in the USA, but I don't know about their fees or deposit options in other countries.

I withdraw to Phoenix wallet over lightning. The request incoming liquidity feature in Phoenix will save you money on miner fees.

I let it pile up in Phoenix until I can move at least 2 million sats to cold storage at once in order to keep those UTXOs large. That will matter a lot in the future.

10 years from now it will be very unfortunate to have a bunch of 100k sat UTXOs in your cold storage. Keep them at least 1 million sats.