A3010 vs A1200 compared well I thought. Games conversions worked just as well on the Archie, despite the lack of graphics acceleration. However I think the A3010 made a better value desktop computer for serious work, despite the cooperative multitasking, as it was about 4 times faster, had a high density floppy drive, and had the whole desktop OS on ROM. The ARM250 may have been only 50% quicker than a 1st generation Archie, but it still compared well to the competition in 1992, especially in an entry-level machine. By 1995 the A3010 had dropped in price to below the 300 pound mark, but the Escom-relaunched A1200 still cost 399 (the same price as the original). Obviously you could get all sorts of CPU upgrades for the A1200 years later, but that's because it was never really superseded. In the Acorn market everyone who wanted a faster machine upgraded to the RiscPC.
As for 1992 vintage PCs I think you overestimate their economy. A budget 386 would have cost a thousand pounds and a Soundblaster would have been a luxury, much less a NIC. The A1200 and A3010 could just have plugged into a TV, no need for a monitor.