I have an E-Machines Futura SX that'll do 1024x768 at 8 bit (plus 24 bit at lower resolutions, and 1152x870 at 8 bit as well). It's not perfect (actually getting 1024x768 out of it requires
an annoying sense-code workaround and I can't get it to work properly in accelerated mode), but they're reasonably cheap, and even unaccelerated, performance is perfectly acceptable by my standards.]
(I should add, my comment in the linked post about the Futura SX not working in A/UX was incorrect - it works fine in A/UX, it was another card in my machine that was upsetting things)