yeah there are always spec'er cars than other cars, and setup is still super important, but it does keep the cars reasonably close to one another, and keeps the costs down as long as you arn't trying to win SCCA runnoffs or something. there are 40 grand spec miatas out there. they make 3 more hp than the 20 grand ones, which make 3 more hp than the 10 grand ones, but on the banking at daytona, 3hp is the difference between 1st and 31st.
that being said, if you get into racing to win, then you will be unhappy. you have to be into racing to race. and that means losing. losing is how you learn to get better, its all part of the system.
I'm excited to race, ill be gunning for a reliable, mid-pack car in the 10-15 grand range, which is pretty common. start racing, and see what happens.