I am proposing that you spend $350 for fly tying tools (most of that number spent on a tying vise) and following that up by dropping another $350 for materials. Seven hundred bucks is a fair bit of money, but you’ve probably shit away as much if not more than this on other hobbies.
Can you spend more than this? Without much of an effort on tools for sure. I’ve made the budget up of the tools I could tie with but not as expensive as the stuff I do tie with. Over time I’ve indulged a little here and there.
Can you spend more on materials? Sure, here and there but it gets a little tougher. The bigger challenge here is to avoid material creep, trying out different colors and substituting materials in the patterns. That’s what gets you. On the other hand, why not? It’s not like a heroin addiction or something.
You don’t have to buy all of this all at once. You can buy materials as the flies you tie require them but the tools are going to remain a big upfront cost. You can go cheaper on the tools (for sure) and on some of the materials, but I hope you won’t. I’ve suggested tools you’ll only have to buy once (except the scissors, sorry, nature of the beast) so at least you feel the pain but once.
With these tools and materials, you should be able to tie ten patterns, up to three color tones in two sizes, a dozen each. If my math is correct it ends up being about 240 flies. Based on the suggested tools and materials, that’s a shade under $3 a fly. I am guessing, but I don’t know, that if you buy another $175 worth of hooks and beads you can tie another 240 from the same materials bringing the cost under $2 a fly.
Let’s forget for a moment about the value of your time. Let’s assume you find this enjoyable enough to set that aside. At $2/fly (and maybe even at $3/fly) you’re probably spending as much as you would in a fly shop.
It’s true that you shouldn’t expect tying flies to save you money, but maybe it’s realistic to think you can break even.