Wow, ok. Think if you really need it. To do a colour change properly, you'd have to strip the car entirely, and do the door jambs, engine compartment and boot - areas which are usually missed on cheap jobs. It looks quite tacky to have contrasting engine bays and door jambs when compared to the exterior. Cheap jobs simply wipe the paint down with a chemical cleaner and then spray straight on - this will probably last around 2 years.
Expensive paint jobs may go as far as to strip your car of all paint, but definitely apply primer to ALL areas, before painting. Don't be surprised to be asked for something like $6000-$8000 for a professional job, which includes a lot of bodywork. You will be so very surprised how many little knocks show up when you have given the car a new lick of paint - so the bondo is usually a must. This may last you 6-8 years.
At the end of the day, the more work you do yourself, the less you will have to pay. Additionally, you get what you pay for.
If you could strike a deal with a painter to do the following yourself
- strip trim
- strip paint
- apply self etching primer
- sand
- apply bondo
- sand
- apply primer
- sand
Then give it to the painter, let them finish it off, by doing their own bondo and sanding, wherever you've missed something - and apply the actual paint. This should cut down on cost significantly. Typically, shops might spend 14-20 days on your body work and maybe just 2 days doing the actual painting. The more effort you put into prep, the more stunning the results.
However, back to square 1 - is it worth it?