Came close about 12 years ago. Had premises lined up, supply agreements sorted with Giant, Orange and Marin plus a couple of others in the wings. Got terms sorted with Madison et al and went on week long cycle mechanic course. Had a 'proper' mechanic lined up and decorators booked.
Landlord let me down at the last minute though and I ended up flogging all the stock I had bought down the local market and to other bike stores.
Just about managed to make enough to come out financially unscathed. Luckily the bikes were sale or return – though I did keep a nice Ti Frame I got at trade. Still got the business plan somewhere – probably on a floppy disk