Hi @JDean1992
I know you’ve said you’d prefer not to use an app but the EasyGift app (https://apps.shopify.com/gifter-cart-auto-include) lets you automatically add gifts to your customer’s cart when a trigger is met (cart value, product quantity or mixture). In your case, you’d want to set up a product rule to automatically add the gifted product when the cart value reaches $25.
You can also set up rules to offer your customer different products in an offer-to-customer type rule, where a popup will show the products you’ve selected will be offered to the customer once the trigger of the rule has been met.
There is a 5-day free trial to let you try it out.
Let me know if you need further help!
Kind regards,
Nathan