for clean gtr tones (and dirty ones too) i use my '65 FENDER Deluxe Reissue or my FENDER Blues Deville (2x12 version).
since neither of those come in at your $400 budget you might wanna check out the ROLAND Cube 80XL. they go for $399.
i have the Cube 60 (very similar..now discontinued) and it's a great little amp for a solid state. besides gtr (elec, acoustic-el, nylon string) i use it to amplify my vibes and i've even used it for low volume bass situations (upright sounds GREAT thru it).
http://www.samash.com/p/Roland_CUBE80XL ... MgodOksA9g
Roland CUBE-80XL: Guitar Amplifier:
The CUBE-80XL delivers 80 screaming watts of power through its 12" high-performance custom speaker. There are discrete, footswitchable* channels — JC Clean and Lead — with Solo settings for each. Twelve COSM® amp models are onboard, including the new Extreme, plus eight effects to choose from, including the new Heavy Octave and COSM vintage Spring Reverb, plus an 80-second Phrase Looper. A 3-band EQ with Presence control is provided for detailing your sound.
80-watt guitar amp with 12" high-performance speaker
Three footswitchable channels, including JC Clean, Lead, and Solo with memory capability
11 COSM amp models, including the new Extreme amp
Eight effects, including the new Heavy Octave and COSM vintage Spring Reverb
80-second Phrase Looper built in
Three-band EQ plus Presence control for fine-tuning your sound