i'm only recommending this b/c it's what i do
i'd look into two amps, both small and neither boutique:
a used fender champ and a new
vox pathfinder 15R.
the champ gives me that american "classic rock" sound (as well as country and blues). plug a strat or a tele into it and you're in tube amp heaven. nice breakup starting around 6 (depending on how hot your pickups are and how hard you play) and full-on drive at 10. it's got a 12ax7 in the pre, a 6v6 in the power and a 5y3 in the rectifier, and it's a whopping 6W. you can dial in a sweet tone and stand right in front of it and not go deaf. oh, and it's got that pristine fender clean, too.
want a different sound, more headroom or grittier grit? play with different tubes.
the pathfinder gives me the british tone. i swear this thing sounds like an AC30. only it's 15W, all solid state, with spring reverb and tremolo, and a 2nd gain-boost channel that gets real nasty (almost too nasty, really--i don't use it much). it's a perfect match for my 2-humbucker ibanez artcore hollowbody and my buddy's ibanez les paul copy that seems to be at my house on permanent loan.
keep the gain low and you're in beatles country, turn the gain to about 5 and you've got a nice crunch and with the gain around 8 or 9 you're in AC/DC territory. the reverb goes from subtle to surf, and the tremolo can easily dial in the "let it be" solo tone without even having to try. oh, and it's a LOUD 15w! i don't need the power but it's nice to know i could gig with it--the speaker out would be perfect for driving a 2x12 at a gig.
both have 8in speakers, and yes both can get a little "farty" sounding when driven exceedingly hard (so don't do that!). however, plugging them into a 1x12 cabinet really makes these amps sing, and it gives them the low-end balls that 8in speakers just don't have. but the 8in speakers certainly have their merit and their place, depending on the tone you're looking for. i'm lucky enough to have a couple 10's at my disposal as well, for when i need it.
anyway, used champs go for around $200--more if you look at a blackface or a tweed, and the vox's are $119 everywhere. add a 12in cabinet to it for around $100, and there's 2 great sounding amps with TONS of tonal flexibility for under $500. *and* the best part is that they're the real deal--none of that modelling or emulation stuff going on.
cheers,
wade