I never even THOUGHT needing a rat rod, fat bike, or any other non-go fast bike...until I bought a single speed to ride the bike trail, and basically gave up my road bike (a super nice Basso frame with Campy components). So - I took the single speed (a $600 Mongoose grey thing) and changed out the bars, took off the rear disc brake and upgraded the front disc, and changed all the other stuff I needed to. It's perfect - for the small amount of $$ I put into it.
Then, the GF said we were spending most of the summer at the beach (Outer Banks, NC), where there isn't a hill, or a trail in sight...but you NEED a decent bike to get to the store and back - due to the friggin horrendous traffic some days. Oh yeah - and to get some exercise
So I had seen a WallyMart fat bike for about $100, and started thinking about that - but I preach that "If you aren't going to spend a few bucks on a decent bike...just walk everywhere; it's less painful"
Started looking at half decent single speed fat bikes, and decided on the El Niño from Felt. Got it on sale for $600, and told myself that I wouldn't fix anything on the bike that disn't need fixing. So I got it, painted it, put new bars on it (after cutting them, painting them, and turning them upside down)...and now I feel like I'm well on my way to rat rodding the heck out of it. (No matter what I tell myself, I am GOING to do more stuff.
"If it ain't broke, fix it 'til it is"