Does anyone know where I can buy proper ball-type F8-16M thrust bearings?
(not too expensively)

That is, thrust bearings where both end ‘washers’ are groved to form a ball-race, and:
one washer is sized to clear the 8mm shaft and fit the 16mm bore,
while the other is sized to fit the 8mm shaft and clear the 16mm bore.

This means that they can provide basic lateral location to the shaft whose thrust they are absorbing.

All I have managed to buy so far (from Feverworks and Sourcingmap), are ones where the washers are identical: both very well made to fit into a 16.0mm bore, and both with a generous centre hole to clear the shaft by a good fraction of a millimetre – so they cannot be used to give any lateral location.

That said, for the low price they cost, they provide lovely smooth operation, even under considerable thust, and everything fits in a 5.0mm stack-height.

Oddly, F8-19M and F8-22M bearings (both 7mm thick, from Sourcingmap) cost almost the same and arrived with proper pairs of differently-sized washers. As far as I can see, these two sizes appear to use ball-cage assemblies with the identical dimensions, it is just that the 22mm types have wider washers.

BTW, you can also get F8-16M ball thrust bearings with washers that are flat with no groove, and lower-profile roller thrust bearing with similarly flat washers, neither of which provide any lateral location.