-who would really want to pay a few random guys to fix their car over a trusted (yet more costly) shop?
-how the hell can we attract business?
My advise
1. You'd be shocked who would be willing to do that
2. Do your first few jobs at cost, go around town and be like "well work for cost, if you bring us the right materials we'll do it for free" do this for 4-5 times get the word out.
My Grandpa started his own repair shop when he was 65 he started out doing it for free just doing oil changes, and tires etc. He had a fully equiped shop. He was working for free (he was retired etc) and business just zoomed up and after about 2 months he started charging he hired his first employee 6 months after starting up. Within 3 yrs the local garage had gone out of business and he's now the only shop in town.
He's now 81 yrs old and makes like $4,000 a month doing nothing. (He doesn't charge a lot for work either) his shop employees get paid just as much as they do else where but my Grandpa doesn't make much. His shop is the most popular in his little region and he's always got plenty of business. He could easily make 3x this or even 4x this but he doesn't care for it. In fact the vast majority of that $4,000 he throws back into the community (he has like 18 rental properties he lives off)
Don't just make it a side business, go full time with it. Take a chance on doing something that you all enjoy doing and if you do good work and market yourselves, you'll have lots of business.
Don't do this
http://smallbiztrends.com/2008/04/startup-failure-rates.html
Within a year 25% of small businesses fail, within 3 years 50%.
I talked to a bar owner who owns a really awesome bar in South Korea and I asked "how was the first year"
He said firs the first 7 months he put money into the bar to keep it running, he got his 1st paycheck on the 8th month the bar finally broke even 23 months into the business...23 months...
Do it part time, if you start finding yourself to busy to keep your day job quit. Because at this point you don't need to work at your Day Job anymore.