Sell yourself. Advertise on Craigslist for free while being cognizant of scammers and low-ballers; run same on RVT.com taking advantage of their free trial period. At the end of the free trial, they typically send an email to you offering advertisement till sold for $19.95. Don't pay for one of the packages from the start, that's the key, you can get it cheaper by just waiting.
Certified documents can ALL be counterfeited and should not be trusted unless they are of last resort, cash in hand is the best way as previously mentioned. I believe IA is a notary state. That being said, ensure you draft a Bill of Sale between you and Buyer and have it notarized as well. The Bill of Sale should cover many items including but not limited to an "as is sale," no warranties, guarantees, promises exist outside the agreement; state/county venue for any future civil litigation if filed, cancellation of insurance/registration at time of sale, etc. It really is a simple process and can flow smoothly with a real buyer.