Every car I have bought in life (and I am talking many hundreds..) have been used.Some have been for retail resale,some just because I see a lot of value in what I am buying.
There are used Atoms available in the $40-$45k range needing mostly good tires to be pretty fast on track,assuming you are truly thinking about an Atom...
Parts are readily available and many upgraded performance parts as well.
Maintenance/repair costs are not unreasonable:most US built Atoms use Cobalt-SS drivetrain components;Ecotec LSJ engines/F35 transaxle,(factory Torsen diffs) These are in Cobalts,Ions and some Saab 9-3's(turbocharged)..fuel pumps,electrics,clutches,etc.
Lots of high performance parts available. Lots.Anything you can dream of..want 1k. HP? GM has one out there racing.
The LNF turbo engine in the newer(08-up) Cobalt SS, HHR and Solstice/Sky will bolt in with minor mods.
A race set of rear billet uprights is $1800,complete.If you track your Atom,a good option to replace the factory stuff.
Good tires for track are about $600pr. rears...500pr. fronts.Seem to wear well enough for multi event use.You can use cheaper tires,but not better..
They don't offer you any kind of climate protection.If it rains,you will get very wet,and driving becomes very challenging.On a hot day,the car is a joy to drive..lots of ventilation.
There is a learning curve to the car,like most cars. Seat time will make you faster,and smile a lot.
People will think you daft.Most think I am anyway,so no loss there.
If you don't like answering questions about your car,don't buy an Atom.(or hide ..)
This is the Atoms 10th year of production and there are many happy owners who would not sell their cars for anything else.
They are not for every one,but what car is?

It's not what you drive, it's how you drive. "Lap times matter"