I think you are off on what it takes to be competitive. I just bought my TAG kart(CRG Rotax) last November for just over $4000 with a ton of spares and some tires. Budgeted for one top end rebuild and a full rebuild for the season. I am very competitive at the GJMS club races. I also went to some of the RMPKC budgeted for about 3 of them. I only bought tires for the race. I would practice on used tires run pump fuel when I could(practice no one really cared). I was running great at IMI until a center seal leak let water into my bottom end killing the rod bearing. The GJ RMPKC I did alright Saturday and Qualified 3rd Sunday. I was laughing all weekend as I was pitted with my pickup an easy up and my tent that I slept in next to a high dollar motor home and trailer. Never once did I think my budget or kart was holding me back.
One of the issues with cost is the perceived cost it takes to race and the actual cost. It is always easier to look at the guy who won and say he won because he out spent you vs he out drove you. I saw this all the time racing DH mountain bikes at a high level in the US and Canada. Guys constantly saying if only I had the money that guys does I could win. When on the track you could visibly see things his riding could improve upon. We need to as a group recognize what is an actual cost to race and what is truly needed and educate new drivers about this. I am hoping to race one SKUSA Pro Tour race next year. I will be there with just my pickup and easy up and tent again. Do I feel like I will be at a disadvantage, no. My driving has more to do with making up tenths on the track then having a freshly rebuilt engine every race. So saying you need a very high budget to be competitive at club races is not right.
There is a big jump from club races to the RMPKC races though. Next week at GJMS I could show up with my kart and for $45 entry/transponder and 5 gallons of pump fuel race on Sunday and have a blast. Now to show up and race the RMPKC we are talking 10 times that cost. I think this gap is something that needs looked at.