As far as I know, there were around 100,000 QLs sold worldwide. Not exactly the success Sinclair Research had hoped for...
Still, it did have a multi-tasking OS and was based on the good old 68K we know and love! I haven't powered my one up for years but I was at least able to track down a disk drive interface for it and transfer stuff from the few QL-formatted Microdrive cartridges I own. Bought the QL, literally "mint in box", from a radio/electronics fair in the UK some time in the 1990s for the princely sum of £5! Bargain!
I'd also love a SAM Coupe, but these are very rare and I've got pretty much zero chance of finding one in New Zealand!!! Shame it was released so late and at a comparatively high cost vs the Atari ST. I'd have had that over the ST if it'd been available in 1988...
Another old rarity I'd like to find is the Enterprise 64 or 128. This was definitely ahead of its time but ended up hitting the market way too late. It could be made to run Spectrum software via a bit of code plus a ROM image file.
- Ali