Verdict
A1 Mini is $100 more for: AMS Lite multi-color compatibility, faster firmware, slightly lower failure rate (4.5% vs ~7%), Bambu Cloud workflow. Ender 3 V3 SE is the absolute price floor — it prints, it has ABL, it costs less than two spools of premium filament.
Buy the A1 Mini if: you have $299 budget and don't want to fiddle. The $100 premium is recovered in failure-reduction savings within 6-9 months at hobby volume.
Buy the Ender 3 V3 SE if: absolute tightest budget, learning printer for kids/students, OK with the tinkering.