Amazon offers the Marshall DSL Series 40-watt Guitar Combo Amplifier for $399.99 with free shipping. (Sweetwater via eBay has it for the same.) That's the lowest price we could find by $100. Features include:
  • 40-watt, all valve, 1x12" Celestion Speaker
  • 2-way footswitch with 2 channels
  • Digital reverb and level control for each channel
  • Shared 5-way EQ: Treble, Middle, Bass, Presence, Resonance
Update: Note that this item is temporarily out of stock, but can still be ordered at this price for delivery when available.