For each room, what is the original color, and what is the new color? If you are making a dramatic change, a tinted primer is the way to go.

Primer is generally cheaper than paint. But even if you prime, be prepared to do two coats.

Invest in good brushes and rollers, and clean them well after use - they will serve you well for decades. And invest in good paint - you do get what you pay for. The biggest cost of the job - the time and effort - are about the same (though cheap paint may not go on as well, or cover as well, so may require additional coats). I have never regretted buying high-end paint.

Good luck with your projects!

So I cant equate
1 coat primer 1 coat paint = 2 coat paint.?

Im going from a bright almost neon blue to a light neutral grey.

How would you go about purchasing paint or paint and primer combo? Im not sure how to spend my money.

Paint and primer are two different things - even though advertised as "paint and primer in one", you can't kill both those birds with one stone.

Experts and pros can no doubt explain better than me, but I'll give it a go (and hopefully get corrected so I can learn in the process).

Primer prepares the walls for painting - whether you are going over brand new drywall texture, or covering up neon blue. Depending on the surface, primer can provide better adhesion between paint and wall.

I don't know much about tinting primer - I always rely on my paint store to help with that decision. I'm not sure if tinting is necessary when going to a light color, but when I painted a hallway hunter green, they tinted the primer a medium gray (I was going over white walls).

Primer (Zinnser 123) $20/gallon
Benjamin Moore Aura: $67/gallon

One coat of primer does not equal one coat of paint! If the coverage is better because of the primer, you save paint.

one coat primer, 2 coats paint