The per-plate cost is actually quite modest, as koraks has intimated. I think you’ve overestimated by quite a bit. I rarely use aluminum ”trophy plate” anymore, simply because it doesn’t give a very good black compared to a japanned tin or an ambrotype. (And it’s actually quite expensive imo)
For years now, I have worked mostly on glass to make collodion negatives, since they offer so much more information to interpret. Nothing beats a print made from a collodion negative. I use glass sourced from my local “dollar store” - it’s found in those Chinese picture frames, and it’s about 1.5mm thick, easily cut to size and probably the cheapest material you can work with. The last time I bought picture frames, I bought the 11x14 inch size, and you can make four 5x7 pieces out of one. That ends up being about 25 cents each. (Note: I think these frames cost more than a dollar these days, but still…)
As for the silver bath, make a volume as big as you can afford: the bigger the volume, the less maintenance you have to do. You do NOT use up the silver bath and then discard it to make a new one, you maintain it by replenishing the silver, kind of like how you replenish a stock developer for re-use. If I make ten plates in one session, I measure the specific gravity of the silver bath at the end of the day, and if it has gone down more than a few points, I add silver nitrate to bring it up to the 1.073 that I typically aim for. Some sessions I do not add more AgNO3 because the SG has not dropped much - you won’t have to add silver after every single session. Often, it takes only a couple of grams - some days it needs only a pinch. Replenishing your silver bath isn’t really such an expensive prospect. The real expense is making the original bath.
The silver bath tank: if you are just working with 4x5 at the start, you don’t have to buy a specialized tank, you CAN just use a tray, as long as you have a way of keeping it in total darkness during the 3 minutes you have a plate sitting in it to sensitize it. It does not have to be a vertically canted tank - those are merely a convenience for those who do lots of plates.
If you haven't already acquired a collodion technique manual, I recommend
Mark Osterman’s manual. It’s inexpensive and great for the beginner, but it doesn’t provide information about anything other than the basics of making tintype positives. If you want more than that, John Coffer’s manual is far more complete (but also far more expensive!).