well the cost is going to depend on what you may or may not have at your disposal. not onlly do you have to remove the swirls and protect the correction you j just did with a good sealant/coating/wax, you will also have to adopt a new car wash routine.
for example, the easiest and fastest way to remove swirls is by machine polishing. im not going to say it is impossible to remove swirls by hand polishing but i know it would be time consuming and tiresome..
so a good DA polisher is going to set you back anywhere between 150-350 dollars, and youll need a dozen pads or so and some quality microfiber towels.
depending on the paint condition, you will need to use a swirl remover/compound first on the entire vehicle, and then a polish to bring up the shine. once polished, you will need to protect all that paint correction with a good sealant/wax/coating of your preference. i prefer sealants and coatings over wax because of their longevity, but this is a personal preference. if you like waxing and have time for it, great!
after sealed and cured, you need to be careful how you wash now. swirls are usually instillled in paint by improper wash techniques. the less you touch the paint the better.
id recommend the two bucket wash method (google it..there are tons of videos out there..Gary Dean has some good ones). after washed, dry the paint with a leaf blower (i know crazy right?) and a waffle weave microfiber while using somehting to aid in drying and prevent waterspots like a quick detailer if you want. Meguar's last touch detail spray works pretty good.
this is just a brief overview, but if you want something more in depth, just PM me.