To be blunt, experience 'fixing and building' and running your own business isn't worth 2 cents unless you can prove it. Everyone and their little brother claims that experience.
If your business is known in the community, or you have an established profssional website, or some way of showing that you do more than slot a new stick of RAM in your family's PC from time to time .. I wouldn't even mention it. If I was the interviewer, I'd just roll my eyes and move on.
I am not a fan of paper certs .. but they are better than nothing and can help you get a foot in the door.
Honestly, I can't really prove my business. I never had a web-site. I advertised by word of mouth, business cards, Craigslist, and some flyers. After a few months of doing it, I got really sick of it. After losing my car, the "business" really tanked. It never grew to the point I needed to actually make real money with it, thus it's always been more of a thing on the side as opposed to my real job. I just figured it would look much better on a resume if I played it off as a real business, but you make a great point. I can't really prove it. I have no more business cards, I had few clients, it never really was much of a business. I don't lie about my skills. I won't say I know Veritas when I have no friggin clue what it is. I'm not afraid to say that I can do this, but not that. I'm always honest and up-front about my skills. However, I will stretch the truth with the business thing. I guess it won't really matter though and I'll probably leave it alone since it will probably do more good than harm.
I did a bit more than replacing RAM. I did some malware removal, some upgrades, mostly consulting. By consulting, I mean the same type of questions we get in the Help me buy/help me build section, but without all the gaming rig questions. Done some custom builds, some hardware trouble shooting, etc. I didn't know squat about networking at the time, but I had more requests for setting up home networks than anything else. I'd be a better fit for that stuff now though. Through all of my jobs while doing the side job, I still learned more working as a tech for another local shop, and just working on my own computers.
I'm not terribly huge on paper certs either. I could just as easily cram for some of the MS and CompTIA stuff as I could actually reading, working, and understanding the material. I think more exams should take Red Hat's certification methods and make everything a hand's on. Red Hat used to have a small multiple choice section, but now the RHCT, RHCE, and RHCA certs are entirely hands-on tests. However, no matter my feelings on certifications, they're my only real hope until I get a significant amount of college or a degree under my belt, or if I get some real, non-retail IT job experience. The latter of which I'll need the former, or some paper certs.