Example: I have wanted to build an electric car for decades (Ok, so I called it a motorized go-kart originally
Common Solution: Get a big DC motor (think fork lift) some thick wire (double O at least) and buy a bunch of expensive parts: high current controller, fancy battery charger, good batteries, etc.
My solution: Take the 25HP 3 phase motor from an industrial air compressor, an AC drive from a locomotive (I think it was more of a street car but that's what the seller said it was from) Some scrounged UPS batteries and individual battery chargers and you have an electric car unlike any other I have found in the hemisphere (There is one a guy in Australia with something similar)
Example: Build a power wheels race car for the PPPRS racing series (check it out on Youtube, Flickr, or the web in general)
Common Solution: Find a power wheels car that you can almost fit into or on, upgrade the motor with a 1HP scooter motor, add some motorcycle sized batteries and drive!
My Solution: Take the smallest power wheels car we found on Craig's list and stretch it to fit little old me! Stick a 6HP winch motor, 2 car sized batteries, and a fork lift motor controller and start doing wheelies (never did get it to do burn outs)
You get the idea. For me its more important to do it myself than to get it done fast or perfectly. I added a garage and rec room to my house. I hired someone to do the foundation (I didn't have the equipment and couldn't learn the skills in a reasonable time), the furnace (I don't have licenses) , and finish the sheet rock (I can finish sheet rock, but it takes for ever and never looks right.) The good news is I built it (with a little help from friends) from brick walls to roof shingles and everything in between. The bad news is it took me 7 years. I really enjoyed those 7 years