When I bought my RV, it was an "individual to individual sale". At the time I understood that there would be NO sales tax on the purchase. This was only partly true. As it turns out, if you purchase an aircraft from an individual and not a "dealer" AND THE SELLER AND BUYER BOTH RESIDE IN THE STATE OF GEORGIA, then there is no sales tax. If the seller is from another state other than Georgia - regardless if its an "individual to individual" or "dealer to individual" sale, there will be sales tax on the purchase amount. The tax percentage will be detirmined by what county you reside in. And since I purchased the plane outside the state of GA I got hit with a surprise tax bill 4 months after I bought the plane. In my case it was 7% of the purchase price. Not a bill I was expecting!!
Also, you will be responisble for a "ad valorem" tax on the airplane every year.
My experience has been that the state will mail you a form asking all sorts of questions about the plane - condition, est value... - for you to fill out and return it to the state. You should recieve a bill in the mail later for the tax amount.
As far as your LLC question - I can'y help there, mine are registered to an individual.
If you're going the LLC route - do look into registering in DE. Many people & companies do this for tax purposes (benifits). Do consult an aviation attorney for help with that though.
Usual disclaimer - just my experience. I delt with this in 2008. The rules may have changed by now. YMMV...
Hope that helps!