Consumables. Durables. Capital investments.
One thing that can be done to control the costs of paints and other consumables is develop some skill in mixing your own colors and then sticking with one brand and line of paint. Modelers who constantly switch brands and lines of paints looking for some “perfect” paint or through a reluctance to mix their own colors (so they constantly buy proprietary mixed “accurate” colors) are caught in a consumer trap, falling for the latest and greatest advertised paints.
Not only do they spend more on paints, but they also spend more for all the ancillary components, like thinners. Buy a color wheel, some pipettes or medicine droppers and learn to mix custom colors. A few minutes spent on the ol’ confuser box researching suggested paint mixes and there’s no need to buy a new jar of paint for that particular color. Just mix it.
The same thing goes for a lot (A LOT!) of the newest “lotions and potions” for other finish and weathering processes.
For example, dry artist pigments are dry artist pigments whether they’re in a small, 1/2 oz special, proprietary “modeler’s product” containers or they’re generic, bulk pigments sold in an arts supply store. The difference is mainly in the price and the label. “Weathering pencils” - the same thing as artist water color pencils, only much more expensive. Oil paints are oil paints. 3D “weathering” and “ground work” texturing paste mediums, smooth or with aggregates, can be found in the arts supply store in big jars or at the hobby shop in small ones. Guess which are cheaper ounce per ounce? Metallic carnauba waxes, such as Bub 'n Buff, have been around for years and years at the arts supply and crafts stores or are “just released” as the newest, best modeling product with your favorite celebrity modeler’s endorsement.
Need to chemically color a set of white metal tracks? You can buy the proprietary, modeler’s brand of “burnishing fluid” or you can buy a bottle of cold gun bluing solution in the sports section of your local big box retailer.
The same might be said for some durable items like airbrushes. Lean to maximize the capability of the air brush that you have until you’ve squeezed every bit of performance you can from it. Only when you then have a need for some additional performance aspect that it cannot provide should you consider adding another airbrush to your kit. Build skills, not a collection of airbrushes.
I’ve only ever had two airbrushes in nearly sixty years of scale modeling. (Although I confess that I did buy two of the same model, so in absolute terms, I have owned three airbrushes in almost sixty years of modeling…) I used my Badger 250 for 30 years (and an earlier copy of the same for about 8 years before I totally broke it - my own fault, BTW). That old Badger is still a good, functional AB that sprays as well today as when it was new. I only bought my second AB, a Rich Pen Phoenix 213C about 15 years ago when I finally decided that I simply would never be able to do some especially fine lines with my Badger. I still use both, BTW, and about a year or so ago, I sent my Badger back to the factory for an overhaul.
The same might be said for air compressors. Again, I’ve only ever had two, and the first one I gave away to a fellow modeler after I had it for about 30 years. It still worked, but I finally wanted a quieter model with a air tank for smooth, pulse-free air supply.
In the end, as mentioned above, tools last a very long time, and, if you wait until you have an actual need for some new tool to get it, tool purchases after some modest initial investments are not really expensive. I have a very well equipped workshop, but I’ve been adding tools to it for decades. I built a ton of models, though, with fewer tools than would fill a shoe box, to include a lot of local and regional contest winners.
The key to controlling the costs of consumables, though, is not to fall for marketing.
Develop your skills, expand your techniques, and gain experience using what you have. Also, there’re are components to your own modeling philosophy that can be looked at.
Put some serious thought into where you really stand on considerations like scale lighting and color. Are you an adherent of the belief that only prototypical color matches are acceptable, or do you believe in the need to “push” shadows and highlights to create and enhance contrasts? Do you believe that a “correct” color can vary from light to dark shades, or is only a monotone application of the prototype color acceptable? Is there an element of artistic interpretation and expression in scale modeling, or is scale modeling about creating mechanical and geometric perfection? Is there a happy medium between these two extremes and do you know where your own preferences and biases stand?
Depending on where you really stand with these concepts, your acceptance or demand for prototype color adherence may or may not demand such a high cost in paints and other consumables. You may find that your artistic position might be a bit more liberating than you once thought.
Follow your own artistic muse, develop your own stylist preferences and biases and liberate yourself from the pressures of marketing.