My pleasure mate. I'm glad bagofbro thought to tag me or I may have missed it.
I understand the budget concerns completely. My approach with supplements is always starting conservative for people I consult because of that. I mean, if I had the money I'd personally spend around $800 a month happily, but nobody has that kind of cash lol. As they get more able to spend, the list expands to whatever their budget is comfortable with.
From my perspective there are a couple possibilities on top supplements. I have to say I really think carb powder to put in your workout drink is essential, but I understand not being big on that and also starting to get intra-workout calories very gradually. Trying it all at once is a sure way to mess with your stomach. In general I consider protein powder food because it IS really just powderized food, but anyway to your question:
BCAAs and beta alanine are probably the two top supplements for a fighter in my opinion.
Beta alanine buffers muscle cell pH during training, so that gnarly burning sensation and the "wall" doesn't hit you as fast. That's really important for fighters going 3-5 minute rounds.
BCAAs are really valuable on calorie restricted diets in my opinion, so anybody cutting weight can see benefit from them. They also improve "time to exhaustion" in studies on endurance. Best use is during training or about 15-20 minutes before a meal. BCAAs are a "trigger" to your metabolism but you still need whole protein sources, so you can pull the trigger prior to a meal and get the ball rolling.
Pill form works just as well as powder for both of those, but is usually significantly more expensive. I mean, you can literally get 1000 grams of beta-alanine powder for around $35, which would last you between 3-9 months lol. Pill form is stupid expensive compared to that. BCAAs are about the same in powder form. I can't link to any places to get them on this forum--even though I love Biotest it's not the most cost-effective method for you--but you can surely google bulk powder suppliers. "pure" "bulk" "supplements" in your search terms. Carb powders are more expensive in general because they're big business right now.
Meal wise, it varies by the person. Typically 2 hours ahead you're fine on solid food rather than a shake, but if you like oatmeal then that's a good place to start. Just experiment with different food sources and find what you feel best on. You can also play with the timing--some people like to eat closer, say 90 minutes, others like 2.5 hours away. Really any healthy food based carb source--rice, oatmeal, potatoes, fruit. If you find you feel hungry again too soon, add some healthy fats like coconut oil or olive oil to slow down digestion--or use a different meat source or carb source--to help keep you from getting hungry. I get hungry really quick after fruit, but starches like rice keep me full longer as does oatmeal. You can also just change the timing of the meal so you're not hungry.
If you're cutting down on carbs in your diet, I would absolutely cut the carbs pre/during workout LAST. Once someone has gradually gotten used to drinking calories during training, I try to keep them in if at all possible because they really help training energy leading into a fight.
EDIT--I forgot, beta alanine is like creatine in that you want blood levels saturated. So there is a loading period, but with a cheap supplement it's not a real problem from a budget stand point.