Auto X is the best way to start and keep cost in check. I started when I was still in college and did not have a trust fund. The hardest part of Auto X for me was finishing and no getting lost in the see of cones. But I got better with seat time.
I also did a few DEs per year as funds permitted. That hooked me on the track. Did DE’s for years and instructed for years all along trying no too race. I was very successful at not racing for a long time. Then kids came on the scene and DEs dried up for a year so I did an arrive and drive open wheel school and it had a few races at the end. That hooked me into racing.
At this point I had many friends racing all sorts of cars in all sorts of sanctioning bodies. So I shopped around for different race classes and was lucky enough to know what all my friends did. I settled on Spece30 and rented a ride from the Drive Gear guys at a few NASA MA races last year. It was all over form their. I pick my car up this Sat. I wont have time for many races but a few weekends a year will keep me sane and the blood flowing.
Drove my track car to the track for years, got a better job, got a truck and trailer, got a better car, tweaked it for a few years, repeat, repeat . . . You see where this goes. Learn to turn some wrenches and you will save a lot of money.
To give you perspective for duration of this addiction. I started my first DE in 92 and am still at it. Nice thing is life is long and you can take it at any speed you want.