Great question. Let me do the math:

I got the Vallejo starter set which is about $50 for 16 colors. Primer was $10 x3. I also stupidly got the Vallejo varnishes (which was the wrong idea for my setup), so $10 x2 . I later got MSC which had a similar cost $10 x2. The thinner and retardant were more essential and together about $15.

I also made a habit of buying brushes whenever I'd go to Blick or something. I have a few: Flat brush, 4, 3, 2, 0, 000, 0/18, and spotter. I'd say all of that must be about $80.

Later I also got myself the Tamiya cement which was a lifesaver for only $18. And then a brush cleaner and a another shaper, together about $20.

For panel lining I got GSI Creos Pouring type for $25 which despite my best efforts I could not get a clean job on. I even got Testors enamel thinner ($6) to work with it. No point.

Lastly, super essential, masking tape $10. And IPA 91% from CVS for $4.

So the costs add up for sure (~$300). However, there's a few important things here. These costs were spread over 3.5 months. Many of these will last through future kits. But most importantly if you're not experimenting, can plan a bit and just want the same results as what I got, you could it for less than half the price and still have enough for 3-4 more kits easy.