You can find plenty of cheap hardware wallets. But if your requirement is open-source with big list of supported altcoins and preferably with an open-source secure element, then you are out of luck. Trezor is working on creating the first almost fully open-source secure element, but I haven't heard any news on that front for months. Foundation Passport seems interesting to me. It's airgapped, open-source, but you won't be happy seeing a price of $250 for Batch 2.

Ratimov originally made a list of 80+ hardware wallets but he is not keeping it updated it seems. This list by FatFork is regularly updated. It's in Croatian but you can see what is available out there and it has links to official websites/stores and price information. Like I said, don't expect the cheap models to to meet all your requirements. Ledger offers more support for altcoins than any of the other popular brands, but it's not open-source. Trezor is, but their altcoin support list is shorter.