As an FYI - we're pretty much known as Team Cheap and if you want to be competitive and do any travel- count on $4K per weekend.
Once you get used to decent tires (aka new tire crack) you don't go back to hard as rocks slicks - besides they are dangerous. If you get a decent amount of track time and you want to drive competitively - figure one set per weekend.
Maintenance is costly if you do it right. Fluids, alignments, etc. and we do this all ourselves.
Brake pads are pretty reasonable- but it's a set $400 - every other event or every 1.5 events.
Being able to run 93 octane is nice- but even that is getting up there.
Travel, hotel, safety equipment if you don't already have it - things like driving suit, HANS device, cool suit, radios, etc. all, IMO, necessary for ANY competitive racing.
Buying a car already sorted out - like Sonny said - is THE BEST way to go.
Whatever you have done in a street car - you have NO IDEA how different it is in a race car - (if you are planning to RACE and not do HPDEs) Yu can do it yourself - but it's a huge investment in equipment, and moreso, in time.
I don't think you'd be sorry buying a well sorted out Comp Coupe. They are really great cars, parts are "reasonable" and there is a ton of support out there from folks like Archer Racing, etc. And - they are not "fussy" - they are great car to start racing - Dodge did a great job of making a car that you can get in and get to 85% very quickly.
Enjoy!