Yes I had a version of tiny Basic I loaded from cassette for Z80.
The sphere was first advertised in back of Radio Electronics in a small box ad. I think it was around June in mid 70s.
It cost if I remember correctly $850 or so. For that it would come with cassette IO, 512 bytes of ROM, a video monitor and case. The boards were on a backplane (inside) with room for expansion. There was also of course a power supply.
This was a kit and not assembled.
At the time Mike did NOT have any inventory and was winging it! I found out later I was his very first order. Also they did a "what do you use your Sphere for" annual contest which I won with my Tank War game and my design for a graphics card. I even sent them a super 8 video of the game play. Sadly lost as I sent my only copy.
That price got you an unassmbled kit. Also at