I have a couple of BSA's gathering dust too. Been collecting parts for YEARS to resurrect whichever I can over the coming winters. The Bonnevilles keep one busy chasing minor repairs and hunting down the correct bits (speedos are costing more than I paid for the ENTIRE BIKE).
Used to be that you could pick up a Bonnie, Trophy, Tiger, Commando, Atlas, Lightning or a Thunderbolt for under a grand running. Last bargain I saw was a Dommie-engined chopper...Purple Paisley, a girder that was at least 7 feet long and a white button-tufted seat. Hadn't seen the road since 1970.....$500.00.
I know of a Fastback and a Hi-Rider tucked away but passed-up a Rocket3 a year ago for $2.5k....the woman at home would have stabbed me in my sleep.
I had a little 500 Tiger when I was about 15 yrs. old. My parents didn't know about it. Great fun. It taught me how to ride (and handled well enough to save me from my mistakes). Sold it to buy a "B"-ville.
Yikes! lol