There aren't easy/comfortable option if you don't use hardware wallet. If you really can't spend lots of money, your only choice is Raspberry Pi 0 (costs $5) and learn about Rapsberry Pi and how to manage your wallet security.
That assume you already have the necessary accessory (Keyboard, Mouse & HDMI Cable).
How about Mycelium? It is easy to install and security is decent.
More secure than custodial wallet? Yes, but the security hugely depends on security practice/awareness of the owner.