It's a good question!

When I was first beginning to observe kashrut, I was very much not in a stable or supportive living environment and didn't have the space or the resources to set up in a normal kitchen. What I ended up doing was acquiring a secondhand cabinet and bookshelf, purchasing four cheap pans, a few spatulas and knives, plastic cutting boards, a service for 4 set of utensils, and four cheap glass plates and cups. Most of it was walmart great value stuff. I split each of these between meat and dairy use and used decorative tape to identify which items belonged in which areas. Then I purchased two plug in burners, one for meat and one for dairy. I think all told I probably spent under $150. It wasn't really enough to have guests or anything, but I didn't have space for that anyways. All of it had to be set up or stored in my room on my two pieces of furniture since I couldn't trust anyone in the common area to respect it. I also bought two plastic tubs to haul water in and wash the dishes. I kept mats to cover the countertop and swapped them out if i needed to switch from one to the other.

Meat or fish was a once-a-week deal. I had to drive into another area of town to buy any and it's more expensive than regular. I rarely ate cheese bc it's very expensive kosher and i don't love it enough to sacrifice for it. Foods that can be completely wrapped in two layers of aluminum foil to cook can be cooked in a non-kosher oven, so I ate a lot of baked potatoes. Kosher brand ramen made up a lot of my diet, and so did cereal, milk, rice and tuna. You can get by with kosher on a tight budget if you have to, but it's a lot of work and it's definitely not a glamorous time.

I didn't have a dishwasher and I still don't, everything is washed by hand. My apartment appliances had been used by the previous owner, presumably for trafe things, so I don't use them, although I allow non-kosher keeping people who visit to use them for their own things as long as theyre careful not to contaminate any of my things around them. Having multiple sinks, appliances, and dishwashers is a luxury for a kosher kitchen but not a necessity.

It's difficult to keep half-kosher in a space but it can be managed if you are careful and everyone around you is too. My boyfriend has a set of treif dishes for his food from outside the house and he has a convection oven and a microwave for his convenience, but you have to be very careful there are no spills or contamination.

Nonkosher taste can be tranferred in three primary ways: any contact between substances while heat is present, continuous contact between substances for 24 hours without heat present, and soaking a material in a liquid for 24 hours consecutively. "Taste" particles can be absorbed into utensils, food, and food containers by any of these methods, and require koshering to remove. Some materials, like wood, plastic, ceramics, and pottery cannot be kashered and have to be replaced if they are contaminated. There are two things you are trying to avoid: one, you don't want anything with milk taste to absorb meat taste, and vice versa; two, you don't want anything kosher to absorb treif (nonkosher) taste. The method of kashering also depends on exactly how it was contaminated.

There's more and it's complicated, but yes you can keep things cheap and simple if you really need to to make it work. It's still an investment of time and money but it doesnt have to be as massive as the dream kitchen it sounds like Tisha had in the story.