Hey, I’ve been a drummer for over 30 years. When I started I got a practice pad. That was really the only option outside of a full set and it worked well. You’ll need to build your fundamentals with rudiments that you can apply on a full kit. This takes some time. That’s not to say you can’t jump into a drum set right away, but I can be a frustrating starting point and as you point out, expensive.
As a work around you can set up other objects around your pad and tap your feet to get a feel for coordination on a full set. Once you’ve made some progress and reach the level of uncontrollable tapping on random objects and air drumming day and night, it’s probably a good indicator you’re in deep and probably need to invest in something.
I will add that buying an electronic kit was the best decision I made, and I wish I had done it earlier, and not been such a purist. The main reason being, I can practice more often, and it provides a more drum like experience.
For a first pad there’s lots of options, gum rubber is a favorite, there are some multi surface pads that you may also want to try, if you want to pretend you’re playing on the worlds tiniest kit. For sticks, start with marching drum sticks or “corps” sticks and get a pair of 5A or 5Bs. Work with the corps sticks for a few months and bring in the smaller sticks to get used to those too. The larger sticks will help you build strength and are over all easier to work with. All this should be obtainable for under $100 USD.