Got a second hand ISA interface SoundBlaster 64 at a computer fair in San Diego when I was visiting there for the best summer of my life in 1998. If I remember correctly it was $4.
At the Scottish Rite Center in Mission Valley? There’s a good chance I was also there that year. My two most prized possessions I acquired there were a 3dfx Voodoo Rush, and a modded PlayStation 1 in a clear plastic housing.
Not there but (and I had to google maps this) it was at a place that I think is called "Pechanga Arena" now on the aptly named "Sports Arena Blvd" but I think the arena was called something else back then. About 2 miles from Ocean / Mission beaches and close to my apartment at the time.
Ah yeah, Pechanga Arena was just “The Sports Arena” in the era before sponsoring venues was a thing. They still to a swap meet in the parking lot of that place every weekend. Random other info about that place, they shot a scene from Almost Famous at one of the freight entrances there.